To provide a wireless system power controller and a power control method capable of further suppressing a standby power requirement.

A multi-channel audio system is constituted in such a way that a transmitting circuit 50 of the player main body and receiving circuits 64 to 47 of the rear loudspeaker 78 are provided and a power source of a rear loudspeaker 78 is operated by radio from a player main body, wherein the receiving circuits receive command data for controlling the power source of the rear loudspeaker 78 from the transmitting circuit 50, the rear loudspeaker 78 turns output of a main power source 72 off by a power source relay 75 and intermittently operates output of a sub-power source 73 by a power source relay 76 when the receiving circuits recognize the command data as a command of power off.