A communication apparatus in a wireless power transmission system includes an operating mode converter configured to switch an operating mode of the communication apparatus between a transmitting mode and a receiving mode according to a predetermined timing; and a transmitting unit configured to transmit state information of a channel occupied by a source including the communication apparatus using a continuous wave signal while the communication apparatus is operating in the transmitting mode irrespective of whether the communication apparatus is performing communication via the occupied channel. The source including the communication apparatus is configured to transmit wireless power. The occupied channel has been assigned to the source including the communication apparatus from a plurality of channels available in a communication cell for assignment to a plurality of sources each configured to transmit wireless power.