To promote power conservation of a controlling circuit for an automobile keyless entry device.

An automobile keyless entry device is equipped with an RF receiving circuit section 5 for receiving a user code transmitted from a key device 6 possessed by a user, a main controlling circuit section 4 for identifying the received user code and, at the same time, for controlling unlocking/locking operation and a sendor module 2 for detecting an approaching state and a contacting state. A second transistor Q2 is provided between power source circuit 3 and RF receiving circuit 5, the second transistor Q2 is turned ON only in the case the human body in a specific area is detected, and power voltage is supplied to the RF receiving circuit 5. Accordingly, power conservation of the keyless entry device can be promoted without supplying dark current unnecessarily.