diff --git a/test/unit/tts_pipeline/test_tts_engines.py b/test/unit/tts_pipeline/test_tts_engines.py
index 1fa32c904..c49bf5462 100644
--- a/test/unit/tts_pipeline/test_tts_engines.py
+++ b/test/unit/tts_pipeline/test_tts_engines.py
@@ -4,7 +4,7 @@
 from fastapi import HTTPException
 
 from voicevox_engine.dev.tts_engine.mock import MockTTSEngine
-from voicevox_engine.tts_pipeline.tts_engine import TTSEngineManager
+from voicevox_engine.tts_pipeline.tts_engine import LATEST_VERSION, TTSEngineManager
 
 
 def test_tts_engines_register_engine() -> None:
@@ -48,6 +48,25 @@ def test_tts_engines_get_engine_existing() -> None:
     assert true_acquired_tts_engine == acquired_tts_engine
 
 
+def test_tts_engines_get_engine_latest() -> None:
+    """TTSEngineManager.get_engine(LATEST_VERSION) で最新版の TTS エンジンを取得できる。"""
+    # Inputs
+    tts_engines = TTSEngineManager()
+    tts_engine1 = MockTTSEngine()
+    tts_engine2 = MockTTSEngine()
+    tts_engine3 = MockTTSEngine()
+    tts_engines.register_engine(tts_engine1, "0.0.1")
+    tts_engines.register_engine(tts_engine2, "0.0.2")
+    tts_engines.register_engine(tts_engine3, "0.1.0")
+    # Expects
+    true_acquired_tts_engine = tts_engine3
+    # Outputs
+    acquired_tts_engine = tts_engines.get_engine(LATEST_VERSION)
+
+    # Test
+    assert true_acquired_tts_engine == acquired_tts_engine
+
+
 def test_tts_engines_get_engine_missing() -> None:
     """TTSEngineManager.get_engine() で存在しない TTS エンジンを取得しようとするとエラーになる。"""
     # Inputs
diff --git a/voicevox_engine/app/application.py b/voicevox_engine/app/application.py
index 90611572f..8315e2dc6 100644
--- a/voicevox_engine/app/application.py
+++ b/voicevox_engine/app/application.py
@@ -80,11 +80,9 @@ def _get_core_characters(version: str | None) -> list[CoreCharacter]:
     )
 
     app.include_router(
-        generate_tts_pipeline_router(
-            tts_engines, core_manager, preset_manager, cancellable_engine
-        )
+        generate_tts_pipeline_router(tts_engines, preset_manager, cancellable_engine)
     )
-    app.include_router(generate_morphing_router(tts_engines, core_manager, metas_store))
+    app.include_router(generate_morphing_router(tts_engines, metas_store))
     app.include_router(
         generate_preset_router(preset_manager, verify_mutability_allowed)
     )
diff --git a/voicevox_engine/app/routers/morphing.py b/voicevox_engine/app/routers/morphing.py
index 458a82333..dd8199757 100644
--- a/voicevox_engine/app/routers/morphing.py
+++ b/voicevox_engine/app/routers/morphing.py
@@ -10,7 +10,6 @@
 from starlette.background import BackgroundTask
 from starlette.responses import FileResponse
 
-from voicevox_engine.core.core_initializer import CoreManager
 from voicevox_engine.metas.Metas import StyleId
 from voicevox_engine.metas.MetasStore import MetasStore
 from voicevox_engine.model import AudioQuery
@@ -24,7 +23,7 @@
     synthesis_morphing_parameter as _synthesis_morphing_parameter,
 )
 from voicevox_engine.morphing.morphing import synthesize_morphed_wave
-from voicevox_engine.tts_pipeline.tts_engine import TTSEngineManager
+from voicevox_engine.tts_pipeline.tts_engine import LATEST_VERSION, TTSEngineManager
 from voicevox_engine.utility.file_utility import try_delete_file
 
 # キャッシュを有効化
@@ -34,9 +33,7 @@
 
 
 def generate_morphing_router(
-    tts_engines: TTSEngineManager,
-    core_manager: CoreManager,
-    metas_store: MetasStore,
+    tts_engines: TTSEngineManager, metas_store: MetasStore
 ) -> APIRouter:
     """モーフィング API Router を生成する"""
     router = APIRouter(tags=["音声合成"])
@@ -89,7 +86,7 @@ def _synthesis_morphing(
         指定された2種類のスタイルで音声を合成、指定した割合でモーフィングした音声を得ます。
         モーフィングの割合は`morph_rate`で指定でき、0.0でベースのスタイル、1.0でターゲットのスタイルに近づきます。
         """
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
 
         # モーフィングが許可されないキャラクターペアを拒否する
diff --git a/voicevox_engine/app/routers/tts_pipeline.py b/voicevox_engine/app/routers/tts_pipeline.py
index 7b113eb39..6555c844c 100644
--- a/voicevox_engine/app/routers/tts_pipeline.py
+++ b/voicevox_engine/app/routers/tts_pipeline.py
@@ -15,7 +15,6 @@
     CancellableEngine,
     CancellableEngineInternalError,
 )
-from voicevox_engine.core.core_initializer import CoreManager
 from voicevox_engine.metas.Metas import StyleId
 from voicevox_engine.model import AudioQuery
 from voicevox_engine.preset.preset_manager import (
@@ -39,6 +38,7 @@
     Score,
 )
 from voicevox_engine.tts_pipeline.tts_engine import (
+    LATEST_VERSION,
     TalkSingInvalidInputError,
     TTSEngineManager,
 )
@@ -65,7 +65,6 @@ def __init__(self, err: ParseKanaError):
 
 def generate_tts_pipeline_router(
     tts_engines: TTSEngineManager,
-    core_manager: CoreManager,
     preset_manager: PresetManager,
     cancellable_engine: CancellableEngine | None,
 ) -> APIRouter:
@@ -85,7 +84,7 @@ def audio_query(
         """
         音声合成用のクエリの初期値を得ます。ここで得られたクエリはそのまま音声合成に利用できます。各値の意味は`Schemas`を参照してください。
         """
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         accent_phrases = engine.create_accent_phrases(text, style_id)
         return AudioQuery(
@@ -116,7 +115,7 @@ def audio_query_from_preset(
         """
         音声合成用のクエリの初期値を得ます。ここで得られたクエリはそのまま音声合成に利用できます。各値の意味は`Schemas`を参照してください。
         """
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         try:
             presets = preset_manager.load_presets()
@@ -175,7 +174,7 @@ def accent_phrases(
         * アクセント位置を`'`で指定する。全てのアクセント句にはアクセント位置を1つ指定する必要がある。
         * アクセント句末に`？`(全角)を入れることにより疑問文の発音ができる。
         """
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         if is_kana:
             try:
@@ -197,7 +196,7 @@ def mora_data(
         style_id: Annotated[StyleId, Query(alias="speaker")],
         core_version: str | SkipJsonSchema[None] = None,
     ) -> list[AccentPhrase]:
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         return engine.update_length_and_pitch(accent_phrases, style_id)
 
@@ -211,7 +210,7 @@ def mora_length(
         style_id: Annotated[StyleId, Query(alias="speaker")],
         core_version: str | SkipJsonSchema[None] = None,
     ) -> list[AccentPhrase]:
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         return engine.update_length(accent_phrases, style_id)
 
@@ -225,7 +224,7 @@ def mora_pitch(
         style_id: Annotated[StyleId, Query(alias="speaker")],
         core_version: str | SkipJsonSchema[None] = None,
     ) -> list[AccentPhrase]:
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         return engine.update_pitch(accent_phrases, style_id)
 
@@ -253,7 +252,7 @@ def synthesis(
         ] = True,
         core_version: str | SkipJsonSchema[None] = None,
     ) -> FileResponse:
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         wave = engine.synthesize_wave(
             query, style_id, enable_interrogative_upspeak=enable_interrogative_upspeak
@@ -294,8 +293,8 @@ def cancellable_synthesis(
                 status_code=404,
                 detail="実験的機能はデフォルトで無効になっています。使用するには引数を指定してください。",
             )
-        version = core_version or core_manager.latest_version()
         try:
+            version = core_version or LATEST_VERSION
             f_name = cancellable_engine._synthesis_impl(
                 query, style_id, request, version=version
             )
@@ -331,7 +330,7 @@ def multi_synthesis(
         style_id: Annotated[StyleId, Query(alias="speaker")],
         core_version: str | SkipJsonSchema[None] = None,
     ) -> FileResponse:
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         sampling_rate = queries[0].outputSamplingRate
 
@@ -374,7 +373,7 @@ def sing_frame_audio_query(
         """
         歌唱音声合成用のクエリの初期値を得ます。ここで得られたクエリはそのまま歌唱音声合成に利用できます。各値の意味は`Schemas`を参照してください。
         """
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         try:
             phonemes, f0, volume = engine.create_sing_phoneme_and_f0_and_volume(
@@ -403,7 +402,7 @@ def sing_frame_volume(
         style_id: Annotated[StyleId, Query(alias="speaker")],
         core_version: str | SkipJsonSchema[None] = None,
     ) -> list[float]:
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         try:
             return engine.create_sing_volume_from_phoneme_and_f0(
@@ -432,7 +431,7 @@ def frame_synthesis(
         """
         歌唱音声合成を行います。
         """
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         try:
             wave = engine.frame_synthsize_wave(query, style_id)
@@ -528,7 +527,7 @@ def initialize_speaker(
         指定されたスタイルを初期化します。
         実行しなくても他のAPIは使用できますが、初回実行時に時間がかかることがあります。
         """
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         engine.initialize_synthesis(style_id, skip_reinit=skip_reinit)
 
@@ -540,7 +539,7 @@ def is_initialized_speaker(
         """
         指定されたスタイルが初期化されているかどうかを返します。
         """
-        version = core_version or core_manager.latest_version()
+        version = core_version or LATEST_VERSION
         engine = tts_engines.get_engine(version)
         return engine.is_synthesis_initialized(style_id)
 
diff --git a/voicevox_engine/cancellable_engine.py b/voicevox_engine/cancellable_engine.py
index 2899fb5e4..a812892f3 100644
--- a/voicevox_engine/cancellable_engine.py
+++ b/voicevox_engine/cancellable_engine.py
@@ -19,7 +19,7 @@
 from .core.core_initializer import initialize_cores
 from .metas.Metas import StyleId
 from .model import AudioQuery
-from .tts_pipeline.tts_engine import make_tts_engines_from_cores
+from .tts_pipeline.tts_engine import LatestVersion, make_tts_engines_from_cores
 
 
 class CancellableEngineInternalError(Exception):
@@ -149,7 +149,7 @@ def _synthesis_impl(
         query: AudioQuery,
         style_id: StyleId,
         request: Request,
-        version: str,
+        version: str | LatestVersion,
     ) -> str:
         """
         音声合成を行う関数
@@ -163,7 +163,7 @@ def _synthesis_impl(
         request: fastapi.Request
             接続確立時に受け取ったものをそのまま渡せばよい
             https://fastapi.tiangolo.com/advanced/using-request-directly/
-        version: str
+        version
 
         Returns
         -------
@@ -245,9 +245,9 @@ def start_synthesis_subprocess(
     while True:
         try:
             query, style_id, version = sub_proc_con.recv()
-            if tts_engines.has_engine(version):
+            try:
                 _engine = tts_engines.get_engine(version)
-            else:
+            except Exception:
                 # バージョンが見つからないエラー
                 sub_proc_con.send("")
                 continue
diff --git a/voicevox_engine/tts_pipeline/tts_engine.py b/voicevox_engine/tts_pipeline/tts_engine.py
index 91de3993a..5cde61724 100644
--- a/voicevox_engine/tts_pipeline/tts_engine.py
+++ b/voicevox_engine/tts_pipeline/tts_engine.py
@@ -2,12 +2,15 @@
 
 import copy
 import math
+from typing import Final, Literal, TypeAlias
 
 import numpy as np
 from fastapi import HTTPException
 from numpy.typing import NDArray
 from soxr import resample
 
+from voicevox_engine.utility.core_version_utility import get_latest_version
+
 from ..core.core_adapter import CoreAdapter, DeviceSupport
 from ..core.core_initializer import CoreManager
 from ..core.core_wrapper import CoreWrapper
@@ -697,6 +700,10 @@ def frame_synthsize_wave(
         return wave
 
 
+LatestVersion: TypeAlias = Literal["LATEST_VERSION"]
+LATEST_VERSION: Final[LatestVersion] = "LATEST_VERSION"
+
+
 class TTSEngineManager:
     """TTS エンジンの集まりを一括管理するマネージャー"""
 
@@ -707,13 +714,18 @@ def versions(self) -> list[str]:
         """登録されたエンジンのバージョン一覧を取得する。"""
         return list(self._engines.keys())
 
+    def _latest_version(self) -> str:
+        return get_latest_version(self.versions())
+
     def register_engine(self, engine: TTSEngine, version: str) -> None:
         """エンジンを登録する。"""
         self._engines[version] = engine
 
-    def get_engine(self, version: str) -> TTSEngine:
+    def get_engine(self, version: str | LatestVersion) -> TTSEngine:
         """指定バージョンのエンジンを取得する。"""
-        if version in self._engines:
+        if version == LATEST_VERSION:
+            return self._engines[self._latest_version()]
+        elif version in self._engines:
             return self._engines[version]
 
         raise HTTPException(status_code=422, detail="不明なバージョンです")