diff --git a/.eslintrc.cjs b/.eslintrc.cjs
index 62bbda1..5f5f4e9 100644
--- a/.eslintrc.cjs
+++ b/.eslintrc.cjs
@@ -71,6 +71,9 @@ module.exports = {
         "plugin:import/recommended",
         "plugin:import/typescript",
       ],
+      rules: {
+        "react/prop-types": "off",
+      },
     },
 
     // Node
diff --git a/app/components/organisms/reception/Calculator.tsx b/app/components/organisms/reception/Calculator.tsx
index b184cc4..499551e 100644
--- a/app/components/organisms/reception/Calculator.tsx
+++ b/app/components/organisms/reception/Calculator.tsx
@@ -1,45 +1,67 @@
-import { Box, Button, HStack, Text, VStack } from "@chakra-ui/react"
+import { Button, Grid, Text, Tooltip, VStack } from "@chakra-ui/react"
 import { FC, memo } from "react"
+import { useCalculator } from "~/hooks/useCalculator"
+import { renderToken } from "~/lib/calculator"
+
+export type CalculatorProps = {
+  total: number
+}
+
+export const Calculator: FC<CalculatorProps> = memo(({ total }) => {
+  const { onInput, clear, tokens, input, calculate } = useCalculator()
 
-export const Calculator: FC = memo(() => {
   return (
-    <Box
-      w="300px"
-      h="250px"
+    <VStack
+      w="fit-content"
       bg="blackAlpha.500"
       borderRadius="10px"
       shadow="lg"
       p={4}
+      gap={4}
     >
-      <VStack>
-        <Text></Text>
-        <HStack>
-          <Button>7</Button>
-          <Button>8</Button>
-          <Button>9</Button>
-          <Button>*</Button>
-        </HStack>
-        <HStack>
-          <Button>4</Button>
-          <Button>5</Button>
-          <Button>6</Button>
-          <Button>-</Button>
-        </HStack>
-        <HStack>
-          <Button>1</Button>
-          <Button>2</Button>
-          <Button>3</Button>
-          <Button>+</Button>
-        </HStack>
-        <HStack>
-          <Button>0</Button>
-          <Button>T</Button>
-          <Button>C</Button>
-          <Button>=</Button>
-        </HStack>
+      <VStack
+        gap={0}
+        py={2}
+        px={4}
+        minH={20}
+        justifyContent="center"
+        alignItems="end"
+        bg="InfoBackground"
+        rounded="md"
+        width="full"
+      >
+        <Text color="GrayText">{tokens.map(renderToken).join(" ")}</Text>
+        <Text color="InfoText" fontSize="xl">
+          {input}
+        </Text>
       </VStack>
-    </Box>
+      <Grid
+        w="fit-content"
+        gap={4}
+        templateColumns="repeat(4, 1fr)"
+        placeItems="center"
+        placeContent="center"
+      >
+        <Button onClick={() => onInput(7)}>7</Button>
+        <Button onClick={() => onInput(8)}>8</Button>
+        <Button onClick={() => onInput(9)}>9</Button>
+        <Button onClick={() => onInput("*")}>×</Button>
+        <Button onClick={() => onInput(4)}>4</Button>
+        <Button onClick={() => onInput(5)}>5</Button>
+        <Button onClick={() => onInput(6)}>6</Button>
+        <Button onClick={() => onInput("-")}>−</Button>
+        <Button onClick={() => onInput(1)}>1</Button>
+        <Button onClick={() => onInput(2)}>2</Button>
+        <Button onClick={() => onInput(3)}>3</Button>
+        <Button onClick={() => onInput("+")}>+</Button>
+        <Button onClick={() => onInput(0)}>0</Button>
+        <Tooltip hasArrow label="合計金額">
+          <Button onClick={() => onInput(total)}>T</Button>
+        </Tooltip>
+        <Button onClick={() => clear()}>C</Button>
+        <Button onClick={() => calculate()}>=</Button>
+      </Grid>
+    </VStack>
   )
 })
-
 Calculator.displayName = "Calculator"
diff --git a/app/hooks/useCalculator.ts b/app/hooks/useCalculator.ts
new file mode 100644
index 0000000..31bdcb1
--- /dev/null
+++ b/app/hooks/useCalculator.ts
@@ -0,0 +1,46 @@
+import { useState } from "react"
+import { calculate as calculateTokens, Token } from "~/lib/calculator"
+
+export const useCalculator = () => {
+  const [tokens, setTokens] = useState<Token[]>([])
+  const [input, setInput] = useState<number>(0)
+
+  const pushToken = (token: Token) => setTokens((prev) => [...prev, token])
+  const popToken = () => setTokens((prev) => prev.slice(0, -1))
+  const clearTokens = () => setTokens([])
+
+  const onInput = (token: Token) => {
+    if (typeof token === "number") {
+      setInput((prev) => Number.parseInt(prev.toString() + token.toString()))
+    } else {
+      pushToken(input)
+      setInput(0)
+      pushToken(token)
+    }
+  }
+
+  const clear = () => {
+    setInput(0)
+    clearTokens()
+  }
+
+  const calculate = () => {
+    const output = calculateTokens([...tokens, input])
+    clearTokens()
+    setInput(output)
+    return output
+  }
+
+  return {
+    tokens,
+    setTokens,
+    pushToken,
+    popToken,
+    clearTokens,
+    input,
+    setInput,
+    onInput,
+    clear,
+    calculate,
+  } as const
+}
diff --git a/app/lib/calculator.ts b/app/lib/calculator.ts
new file mode 100644
index 0000000..8a1e5e1
--- /dev/null
+++ b/app/lib/calculator.ts
@@ -0,0 +1,124 @@
+export type ParenthesisToken = "(" | ")"
+
+export type OperatorToken = "+" | "-" | "*" | "/"
+
+export type Token = number | OperatorToken | ParenthesisToken
+
+export type Expression = Num | Operator
+
+export type Num = {
+  type: "number"
+  value: number
+  lhs?: Expression
+  rhs?: Expression
+}
+
+export type Operator = {
+  type: "operator"
+  value: OperatorToken
+  lhs: Expression
+  rhs: Expression
+}
+
+export const renderToken = (token: Token): string => {
+  switch (token) {
+    case "*":
+      return "×"
+    case "-":
+      return "−"
+    default:
+      return token.toString()
+  }
+}
+
+export const isOperator = (token?: Token): token is OperatorToken =>
+  token === "+" || token === "-" || token === "*" || token === "/"
+
+export const isNumber = (token?: Token): token is number =>
+  typeof token === "number"
+
+export const calculate = (tokens: Token[]): number => {
+  const expr = parse(tokens)
+  return calculateExpr(expr)
+}
+
+const calculateExpr = (expr: Expression): number => {
+  if (expr.type === "number") {
+    return expr.value
+  }
+
+  if (expr.type === "operator") {
+    const lhs = calculateExpr(expr.lhs)
+    const rhs = calculateExpr(expr.rhs)
+    switch (expr.value) {
+      case "+":
+        return lhs + rhs
+      case "-":
+        return lhs - rhs
+      case "*":
+        return lhs * rhs
+      case "/":
+        return lhs / rhs
+    }
+  }
+  throw new Error("Invalid expression")
+}
+
+// primary = "(" expr ")" | number
+const parsePrimary = (tokens: Token[]): [Expression, Token[]] => {
+  const token = tokens[0]
+  if (token === "(") {
+    const [expr, rest] = parseExpr(tokens.slice(1))
+    if (rest[0] !== ")") {
+      throw new Error("Invalid expression, expected ')'")
+    }
+    return [expr, rest.slice(1)]
+  }
+  if (typeof token === "number") {
+    return [{ type: "number", value: token }, tokens.slice(1)]
+  }
+  throw new Error("Invalid expression, expected number or '('")
+}
+
+// mul = primary ("*" primary | "/" primary)*
+const parseMul = (tokens: Token[]): [Expression, Token[]] => {
+  let [lhs, rest] = parsePrimary(tokens)
+  while (rest.length > 0) {
+    const token = rest[0]
+    if (token === "*" || token === "/") {
+      const [rhs, rest2] = parsePrimary(rest.slice(1))
+      lhs = { type: "operator", value: token, lhs, rhs }
+      rest = rest2
+    } else {
+      break
+    }
+  }
+  return [lhs, rest]
+}
+
+// expr = mul ("+" mul | "-" mul)*
+const parseExpr = (tokens: Token[]): [Expression, Token[]] => {
+  let [lhs, rest] = parseMul(tokens)
+  while (rest.length > 0) {
+    const token = rest[0]
+    if (token === "+" || token === "-") {
+      const [rhs, rest2] = parseMul(rest.slice(1))
+      lhs = { type: "operator", value: token, lhs, rhs }
+      rest = rest2
+    } else {
+      break
+    }
+  }
+  return [lhs, rest]
+}
+
+/**
+ * 数式のトークン列をパースして、計算順序を表す木構造を返す
+ */
+const parse = (tokens: Token[]): Expression => {
+  const [expr, rest] = parseExpr(tokens)
+  if (rest.length > 0) {
+    throw new Error("Invalid expression")
+  }
+  return expr
+}
diff --git a/app/routes/reception.tsx b/app/routes/reception.tsx
index efd7dea..7bb9930 100644
--- a/app/routes/reception.tsx
+++ b/app/routes/reception.tsx
@@ -239,7 +239,7 @@ export default function Reception() {
                   />
                 </FormControl>
               </Stack>
-              <Calculator />
+              <Calculator total={total} />
             </VStack>
           </ModalBody>
           <ModalFooter gap={4}>