To make transmission power constant regardless of the fluctuation of a transmission distance and also to enable the stable transmission of operation power with a simple circuit configuration by allowing an active module transmitting power to automatically control a power transmission output on the basis of the receiving strength of an information signal received from a passive module.

An active module A transmits power and an information signal including a command control signal from the power transmitting head 4 of a power transmitting part including an oscillation circuit of a frequency for power transmission and transmits the power and the command control signal to a passive module B at a relatively adjacent distance in an non-contact way due to electromagnetic inductive coupling and optical coupling. The module B uses power supplied to a power receiving head 5 as power supply for operation. The module B further transmits a detection signal of signal strength related to the receiving strength of the information signal and receiving power variation as FM waves from a signal transmitting head 11 to the module A. The module A receives the FM waves and performs the output control of an oscillation circuit 1 in accordance with a detection signal extracted by demodulating the FM waves.