PURPOSE: To reduce the load of a central processing unit (CPU) as much as possible and to reduce energy consumption by detecting an idle state in the manner of a hardware and automatically turning the device to a standby state by judging the idle state without depending on the processing program of the CPU.

CONSTITUTION: This device is equipped with an internal integrated circuit 11 to process signals, power control means 12 to control the power of the internal integrated circuit 11, and self-detection/standby control means 13 to control the power control means 12 and based on a state transition signal S1 related to the internal integrated circuit 11, the self-detection/standby control means 13 outputs a standby control signal S2 to the power control means 12.