diff --git a/backend/alembic/versions/c1a2b3d4e5f6_add_reason_and_normalize_status.py b/backend/alembic/versions/c1a2b3d4e5f6_add_reason_and_normalize_status.py
new file mode 100644
index 0000000..3f57274
--- /dev/null
+++ b/backend/alembic/versions/c1a2b3d4e5f6_add_reason_and_normalize_status.py
@@ -0,0 +1,31 @@
+"""add reason column to events and normalize status (dismissed → false_alarm)
+
+Revision ID: c1a2b3d4e5f6
+Revises: 3dfc3e213f69
+Create Date: 2026-05-11 16:00:00.000000
+
+- events.reason String NULL 컬럼 추가
+- 기존 status='dismissed' 행을 'false_alarm' 으로 백필 (frontend 와 정렬)
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'c1a2b3d4e5f6'
+down_revision: Union[str, None] = '3dfc3e213f69'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column('events', sa.Column('reason', sa.String(), nullable=True))
+    # frontend 가 'false_alarm' 을 기대 → 기존 'dismissed' 행 백필
+    op.execute("UPDATE events SET status='false_alarm' WHERE status='dismissed'")
+
+
+def downgrade() -> None:
+    op.execute("UPDATE events SET status='dismissed' WHERE status='false_alarm'")
+    op.drop_column('events', 'reason')
diff --git a/backend/app/api/events.py b/backend/app/api/events.py
index c94e90b..6311193 100644
--- a/backend/app/api/events.py
+++ b/backend/app/api/events.py
@@ -77,7 +77,7 @@ async def get_event_stats(
     today_total = await db.scalar(select(func.count(Event.id)).where(Event.timestamp >= start_of_day))
     pending_count = await db.scalar(select(func.count(Event.id)).where(Event.status == 'pending'))
     confirmed_count = await db.scalar(select(func.count(Event.id)).where(Event.status == 'confirmed'))
-    false_alarm_count = await db.scalar(select(func.count(Event.id)).where(Event.status == 'dismissed'))
+    false_alarm_count = await db.scalar(select(func.count(Event.id)).where(Event.status == 'false_alarm'))
     
     return {
         "today_total": today_total or 0,
@@ -122,7 +122,8 @@ async def create_event(
     - AI 추론 엔진(inference.py)에서 호출됩니다.
     """
     # 1. DB에 사건 기록 (Persistence)
-    event = Event(**body.model_dump())
+    # exclude_none: 비전송 필드는 모델 default 가 적용되도록 (event_type → 'unknown')
+    event = Event(**body.model_dump(exclude_none=True))
     db.add(event)
     await db.flush()
 
@@ -159,7 +160,8 @@ async def report_false_alarm(
     if not event:
         raise HTTPException(status_code=404, detail="해당 사건 기록을 찾을 수 없습니다.")
         
-    event.status = "dismissed"
+    event.status = "false_alarm"
+    event.reason = body.reason
     event.handled_by = current_admin.id
     event.handled_at = datetime.now()
     
diff --git a/backend/app/models/models.py b/backend/app/models/models.py
index 0693c9e..bf73b8c 100644
--- a/backend/app/models/models.py
+++ b/backend/app/models/models.py
@@ -41,8 +41,9 @@ class Event(Base):
     clip_url: Mapped[Optional[str]] = mapped_column(String, nullable=True)
     track_id: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
     confidence: Mapped[Optional[float]] = mapped_column(Float, nullable=True)
-    status: Mapped[str] = mapped_column(String, default="pending")  # pending | confirmed | dismissed
-    event_type: Mapped[str] = mapped_column(String, default="unknown")  # tag_fail | jump | emergency_door
+    status: Mapped[str] = mapped_column(String, default="pending")  # pending | confirmed | false_alarm
+    event_type: Mapped[str] = mapped_column(String, default="unknown")  # tailgating | unpaid | jump | crawling | unknown
+    reason: Mapped[Optional[str]] = mapped_column(String, nullable=True)  # status == "false_alarm" 일 때 오탐 사유
     handled_by: Mapped[Optional[int]] = mapped_column(Integer, ForeignKey("admins.id"), nullable=True)
     handled_at: Mapped[Optional[datetime]] = mapped_column(DateTime, nullable=True)
 
diff --git a/backend/app/schemas/schemas.py b/backend/app/schemas/schemas.py
index b6eaba0..0acdad3 100644
--- a/backend/app/schemas/schemas.py
+++ b/backend/app/schemas/schemas.py
@@ -45,6 +45,7 @@ class EventCreate(BaseModel):
     clip_url: Optional[str] = None
     track_id: Optional[int] = None
     confidence: Optional[float] = None
+    event_type: Optional[str] = None  # AI 가 분류 결과를 함께 전송 (없으면 모델 default 'unknown')
 
 
 class EventResponse(BaseModel):
@@ -55,6 +56,8 @@ class EventResponse(BaseModel):
     track_id: Optional[int]
     confidence: Optional[float]
     status: str
+    event_type: str
+    reason: Optional[str] = None
     handled_by: Optional[int]
     handled_at: Optional[datetime]
 
@@ -62,7 +65,7 @@ class EventResponse(BaseModel):
 
 
 class EventStatusUpdate(BaseModel):
-    status: Literal["confirmed", "dismissed"]
+    status: Literal["confirmed", "false_alarm"]
 
 
 # ── Notification ──────────────────────────────────────────────────────────────