A first communicator of a first communication device is configured to use a first wireless channel and execute first key-exchange processing at a timing at which a first key-exchange timer expires. A second communicator of the first communication device is configured to use a second wireless channel and execute second key-exchange processing at a timing at which a second key-exchange timer expires. When streaming data are transmitted by using one wireless channel of the first wireless channel and the second wireless channel and a difference between a first key-exchange timer value and a second key-exchange timer value is greater than a predetermined range, a control circuit is configured to change a wireless channel used for transmission to the other wireless channel before key-exchange processing in the one wireless channel is started.