A power supply control unit starts power supply to an endoscope if an external trigger is applied (Step S10) (Step S12). If the power supply to the endoscope is started, the endoscope becomes operable. As a result, voltage information showing a current voltage value Vrect is transmitted from the endoscope to the processor device for an endoscope through optical communication as feedback information. A control unit of the processor device for an endoscope receives the voltage information showing the current voltage value Vrect, and outputs the received voltage information to a power supply control unit (Step S14). The power supply control unit adjusts the frequency of an electric current made to flow to a power transmitting coil of a power supply unit, on the basis of the received voltage information (Steps S16 to S24).
