To provide a power feeding method in which a power source box, etc., does not need to be arranged at the side of a USB device even when a wireless apparatus is connected by USB to a peripheral device, etc.

When power is fed to the wireless apparatus 5 at the side of the peripheral device 3 between the wireless apparatuses 4, 5 which are arranged in each one of a host device 1 and the peripheral device 3 connected via the USB, etc., so as to exchange data, power is fed to the wireless apparatus 5 via the power source of the peripheral device 3. Power is fed through the use of one cable 19 in the case of feeding power via a plug 13 having a power source terminal 16 arranged in the wireless apparatus 20, a connector 14 having a power source terminal 17 arranged in the peripheral device 3 and the cable 19 for connecting the connector 14 and the plug 13. A path for feeding power via the cable by which the power source is supplied from the peripheral device is arranged so as to feed power from the peripheral device to the wireless apparatus. Consequently, it is not required to feed power from the side of the USB host device.