To prevent malfunction repeating locking/unlocking of a door lock during the traveling of a car by stopping the door lock even when a specific signal is not received during the traveling of the car in a device for releasing the door lock when the specific signal is received from a transmitter and for locking the door when the specific signal is not received.

A receiving circuit 21 receives radio waves from a transmitter through an antenna 22, and they are detected by a tuner circuit 29 to amplify and are outputted to a CPU 23. A door lock output circuit 26 drives a door lock actuator 25 in accordance with a door lock signal from the CPU 23. When a radio signal (ID code and door lock releasing signal) from the transmitter is received, an auto-door lock is stopped, and when the radio signal is not received, the auto-door lock is made. Then, when an on-signal of a brake switch is not outputted from a parking brake switch 27, the CPU 23 decides that the car is still traveling, and door lock control is stopped even if a signal is not received from the transmitter.