PURPOSE: To reduce the number of switches to two thereby improving the operability of a key by providing a control means for outputting a signal to effect another function different from the functions of first and second switches, when a continuous period of a received signal exceeds a predetermined period.

CONSTITUTION: When a door-lock switch 1 is turned on for a short period of time T1, a code signal is outputted as radio waves by a first code making circuit 24 through a transmitting circuit 10 and an antenna 11. When the code signal is received by a receiver, the code signal is decoded by a code decoding and time judging circuit 14 and it is judged that the signal represents 'door lock', a control signal is outputted to a first driver 16 through a control circuit 15 to lock a door. And when the door-lock switch 1 is kept 'on' for a period T3 longer than the period T1, a pulse having pulse width T2 is supplied to a first OR gate 22 from a first one-shot multivibrator 20, while a pulse having the same pulse width T3 is supplied from a first interface 4. And it is judged that the received signal is longer than the period T2, a code signal representing 'trunk open' is decoded and a control signal P5 is outputted to a second driver 17, following a pulse P4.