diff --git a/addon/access_token.py b/addon/access_token.py
new file mode 100644
index 0000000..6f1c8bb
--- /dev/null
+++ b/addon/access_token.py
@@ -0,0 +1,155 @@
+import re
+from dataclasses import dataclass, asdict
+from typing import List, Dict, Optional, Any
+
+from mitmproxy.http import HTTPFlow
+
+import lib.target as target
+from lib.report import save_report
+
+# 결과 리포트 저장용 데이터 클래스
+@dataclass
+class TokenLeakResult:
+    title: str
+    description: str
+    uri: str
+    status: str = "MEDIUM" # 기본 상태
+
+    def to_report(self, target_value) -> Dict[str, str]:
+        """리포트 저장 포맷(dict)으로 변환"""
+        return {"target": target_value, **asdict(self)}
+
+
+# 요청/응답에서 액세스 토큰 노출 여부를 검사하는 스캐너
+class AccessTokenScanner:
+
+    async def scan(self, flow: HTTPFlow) -> None:
+        """단일 HTTPFlow(request + response)에 대해 요청과 응답을 모두 검사."""
+        print(f"[TOKENDEBUG] Request URL: {flow.request.url}")
+        findings: List[TokenLeakResult] = []
+
+        findings.extend(await self._scan_request(flow.request))
+        findings.extend(await self._scan_response(flow.response, flow.request.url))
+
+        if findings:
+            target_value = target.load()
+            save_report([f.to_report(target_value) for f in findings])
+
+    # 내부 구현
+    async def _scan_request(self, request: Any) -> List[TokenLeakResult]:
+        results: List[TokenLeakResult] = []
+        
+        print("[TOKENDEBUG] ==scan request==")
+        # URL 검사
+        token_result = self._extract_token(request.url)
+        if token_result:
+            token, has_bearer = token_result
+            results.append(
+                TokenLeakResult(
+                    title="Token Leak in Request URL",
+                    description=f"요청 URL에 토큰이 포함되어 있습니다 (앞 20자): {token[:20]}…",
+                    uri=request.url,
+                    status="MEDIUM" if has_bearer else "LOW"
+                )
+            )
+
+        # Body 검사 (텍스트 컨텐츠인 경우)
+        if request.content:
+            body_text = request.get_text(strict=False)
+            token_result = self._extract_token(body_text)
+            if token_result:
+                token, has_bearer = token_result
+                results.append(
+                    TokenLeakResult(
+                        title="Token Leak in Request Body",
+                        description=f"요청 본문에 토큰이 포함되어 있습니다 (앞 20자): {token[:20]}…",
+                        uri=request.url,
+                        status="MEDIUM" if has_bearer else "LOW"
+                    )
+                )
+
+        return results
+
+    async def _scan_response(self, response: Optional[Any], request_url: str) -> List[TokenLeakResult]:
+        if response is None:
+            return []
+
+        results: List[TokenLeakResult] = []
+        print("[TOKENDEBUG] ==scan response==")
+        # Location 헤더 검사 (리다이렉트)
+        if location_header := response.headers.get("Location"):
+            token_result = self._extract_token(location_header)
+            if token_result:
+                token, has_bearer = token_result
+                if has_bearer:
+                    results.append(
+                        TokenLeakResult(
+                            title="Token Leak in Redirect URL (Location header)",
+                            description=f"Location 헤더에 토큰이 노출되었습니다 (앞 20자): {token[:20]}…",
+                            uri=location_header,
+                        )
+                    )
+
+        # Body 검사 (텍스트 컨텐츠인 경우)
+        if response.content:
+            body_text = response.get_text(strict=False)
+            token_result = self._extract_token(body_text)
+            if token_result:
+                token, has_bearer = token_result
+                if has_bearer:
+                    results.append(
+                        TokenLeakResult(
+                            title="Token Leak in Response Body",
+                            description=f"응답 본문에 토큰이 노출되었습니다 (앞 20자): {token[:20]}…",
+                            uri=request_url,
+                        )
+                    )
+
+        return results
+
+    # 토큰 탐지 키워드드
+    _TOKEN_KEYS = [
+        "access_token",
+        "accesstoken",
+        "refresh_token",
+        "refreshtoken",
+        "auth_token",
+        "session_token",
+        "secret_token",
+        "ssoauth",
+    ]
+
+    # "bearer" 표시가 동시에 존재할 때만 토큰으로 판단하여 false positive를 줄임
+    _TOKEN_TYPE_REGEXES = [
+        re.compile(r"token[_-]?type[=:]?\s*bearer", re.IGNORECASE),
+        re.compile(r"authorization\s*[:=]\s*bearer", re.IGNORECASE),
+    ]
+
+    # 동적 컴파일: key=value / "key": "value" / Bearer <token>
+    _TOKEN_PATTERNS = (
+        [
+            re.compile(fr"{key}[=:]\s*([A-Za-z0-9\-._~+/]{{10,}})", re.IGNORECASE)
+            for key in _TOKEN_KEYS
+        ]
+        + [
+            re.compile(fr"\"{key}\"\s*:\s*\"([^\"]{{10,}})\"", re.IGNORECASE)
+            for key in _TOKEN_KEYS
+        ]
+        + [re.compile(r"bearer\s+([A-Za-z0-9\-._~+/]{10,})", re.IGNORECASE)]
+    )
+
+    def _extract_token(self, text: str) -> Optional[str]:
+        """텍스트 블록에서 토큰 후보를 추출. Bearer 유형이 동반된 경우에 한정."""
+        if not text:
+            return None
+
+        # Bearer 타입이 같이 존재하는지 미리 확인 (속도 & 정확도↑)
+        has_bearer = any(rx.search(text) for rx in self._TOKEN_TYPE_REGEXES)
+
+        for pattern in self._TOKEN_PATTERNS:
+            if (m := pattern.search(text)) and m.group(1):
+                print(f"[TOKENDEBUG] token: {m.group(1)}")
+                print(f"[TOKENDEBUG] has_bearer: {has_bearer}")
+                return m.group(1), has_bearer
+        print("[TOKENDEBUG] No matched.")
+        return None
diff --git a/addon/init.py b/addon/init.py
index 1ef743d..c485248 100644
--- a/addon/init.py
+++ b/addon/init.py
@@ -4,6 +4,7 @@ from pkce_check import PKCEDowngradeChecker
 from ScopeDetection import ScopeDetection
 from csrf_check import CsrfChecker
 from nonce_check import NonceChecker
+from access_token import AccessTokenScanner
 
 class PKCEAddon:
     def __init__(self):
@@ -61,4 +62,17 @@ class NonceAddon:
             print(f"[ERROR] NonceAddon failed: {e}")
             pass
 
-addons = [PKCEAddon(), ScopeAddon(), CsrfAddon(), NonceAddon()]
+
+class AccessTokenAddon:
+    def __init__(self):
+        self.checker = AccessTokenScanner()
+
+    async def response(self, flow: http.HTTPFlow):
+        try:
+            await self.checker.scan(flow)
+        except Exception as e:
+            print(f"[ERROR] AccessToken Addon failed: {e}")
+            pass
+    
+
+addons = [PKCEAddon(), ScopeAddon(), CsrfAddon(), NonceAddon(), AccessTokenAddon()]