diff --git a/.gitignore b/.gitignore
index 2f04a14..09bb46a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -132,4 +132,5 @@ dmypy.json
 .history
 
 # Test
+test.py
 test/
diff --git a/README.md b/README.md
index ee87a3b..a4dccb6 100644
--- a/README.md
+++ b/README.md
@@ -53,4 +53,30 @@ print(f"{str6} -> {punycode.convert(str6)}")
 # xn--n8jub8754b.xn--rhqv96g -> 美しい.世界
 # xn--28j2af.xn--q9jyb4c -> こっち.みんな
 # xn--wgv71a119e.jp -> 日本語.jp
+```
+
+## ascii_only option (v0.2.0 or later)
+
+If you don't want to convert a Punycode domain to Unicode when you use `convert()` function, you can use `ascii_only` option.
+
+With this option `True`, `convert()` will convert only Unicode domains.
+
+```python
+# ascii_only option (v0.2.0 or later)
+ascii_only = True
+
+# Only Unicode domains will be converted if ascii_only=True
+print(f"{str4} -> {punycode.convert(str4, ascii_only)}")
+print(f"{str5} -> {punycode.convert(str5, ascii_only)}")
+print(f"{str6} -> {punycode.convert(str6, ascii_only)}")
+
+# xn--n8jub8754b.xn--rhqv96g -> xn--n8jub8754b.xn--rhqv96g
+# xn--28j2af.xn--q9jyb4c -> xn--28j2af.xn--q9jyb4c
+# xn--wgv71a119e.jp -> xn--wgv71a119e.jp
+```
+
+This option is available on 0.2.0 or later version, so if you use v0.1.0, please update `punycode`.
+
+```powershell
+pip install -U punycode
 ```
\ No newline at end of file
diff --git a/punycode/punycode.py b/punycode/punycode.py
index 980ece7..7e57952 100644
--- a/punycode/punycode.py
+++ b/punycode/punycode.py
@@ -1,10 +1,13 @@
 import idna
 
-def convert(input_text:str):
+def convert(input_text:str, ascii_only=False):
     if not isinstance(input_text, str):
         raise ValueError("Input must be string.")
     if (input_text[:4] == "xn--") | (".xn--" in input_text):
-        output_text = idna.decode(input_text)
+        if ascii_only:
+            output_text = idna.encode(input_text).decode('utf-8')
+        else:
+            output_text = idna.decode(input_text)
     else:
         output_text = idna.encode(input_text).decode('utf-8')
     return output_text
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 9143476..5feae59 100644
--- a/setup.py
+++ b/setup.py
@@ -15,7 +15,7 @@ def _requirements():
 setup(
     name=package_name,
     description='Punycode Converter Library for Python',
-    version='0.1.0',
+    version='0.2.0',
     long_description=long_description,
     long_description_content_type='text/markdown',
     url='https://github.com/Yutsuro/punycode',