According to an embodiment, a communication device is provided in a movable body and is wirelessly communicable with a transceiver unit and another movable body. A receiver of the device receives transceiver unit information including traffic-light information that the transceiver unit has transmitted to a predetermined channel. An processing circuitry extracts the traffic-light information corresponding to a running direction of the movable body from the transceiver unit information. A transmitter transmits movable body information of the movable body to the predetermined channel. A processing circuitry controls a transmission timing of the movable body information such that a transmission control period becomes a preset first time. A processing circuitry changes the transmission control period to a second time longer than the first time, when the traffic-light information with respect to the running direction indicates a stopping command, and a speed of the movable body is a preset speed or less.