To provide an automatic alarm device, which alarms a user after the situation that should require alarm issuance is ascertained.

Upon acquiring an ID code identical to a reference ID code, a security ECU 35 recognizes that a corresponding electronic key 2 is used. A touch sensor 41 detects that a door outside handle is touched. The security ECU 35 allows an alarm 50 to be operated, when the operation of the door outside handle is detected by the touch sensor 41, in a state where use of the corresponding electronic key 2 is not recognized.