A communication system, comprising: first and second master stations (12a, 12b) configured to perform synchronous wireless communication with a slave station (11a, 11b, 11c) via a first network; and a control station configured to be connected to the first and second master stations (12a, 12b) via a second network, wherein the control station is configured to transmit time information used to synchronize times of a clock device included in the first master station and a clock device included in the second master station to each of the first and second master stations (12a, 12b) via the second network, wherein the first master station is configured to transmit the time information as announcement information to the second master station via the first network when receiving the time information from the control station, the second master station is configured to transmit the time information as announcement information to the first master station via the first network when receiving the time information from the control station, the first master station is configured to receive the announcement information transmitted from the second master station via the first network, the second master station is configured to receive the announcement information transmitted from the first master station via the first network, the first master station is configured to calculate reception quality information, which indicates reception quality of the announcement information transmitted from the second master station via the first network, to transmit to the control station via the second network, the second master station is configured to calculate reception quality information, which indicates reception quality of the announcement information transmitted from the first master station via the first network, to transmit to the control station via the second network, the control station is configured to instruct one of the first and second master stations (12a, 12b) to serve as a master and the other of the first and second master stations (12a, 12b) to serve as a slave based on the reception quality information from the first and second master stations (12a, 12b), the master is configured to perform timing of the clock device included in the master based on the time information from the control station, and the slave is configured to perform timing of the clock device included in the slave based on the announcement information transmitted from the master via the first network. first and second master stations (12a, 12b) configured to perform synchronous wireless communication with a slave station (11a, 11b, 11c) via a first network; and a control station configured to be connected to the first and second master stations (12a, 12b) via a second network, wherein the control station is configured to transmit time information used to synchronize times of a clock device included in the first master station and a clock device included in the second master station to each of the first and second master stations (12a, 12b) via the second network, wherein the first master station is configured to transmit the time information as announcement information to the second master station via the first network when receiving the time information from the control station, the second master station is configured to transmit the time information as announcement information to the first master station via the first network when receiving the time information from the control station, the first master station is configured to receive the announcement information transmitted from the second master station via the first network, the second master station is configured to receive the announcement information transmitted from the first master station via the first network, the first master station is configured to calculate reception quality information, which indicates reception quality of the announcement information transmitted from the second master station via the first network, to transmit to the control station via the second network, the second master station is configured to calculate reception quality information, which indicates reception quality of the announcement information transmitted from the first master station via the first network, to transmit to the control station via the second network, the control station is configured to instruct one of the first and second master stations (12a, 12b) to serve as a master and the other of the first and second master stations (12a, 12b) to serve as a slave based on the reception quality information from the first and second master stations (12a, 12b), the master is configured to perform timing of the clock device included in the master based on the time information from the control station, and the slave is configured to perform timing of the clock device included in the slave based on the announcement information transmitted from the master via the first network.