A communication device performs information communication through a communication line based on communication data specified by a CAN protocol. A communication necessity determination unit determines whether or not the information communication through the communication line is necessary based on external information obtained from an external device. When the information communication is necessary and a communication error is detected, a communication control unit stops the information communication during a fixed period and restarts the information communication after the fixed period elapses. When the information communication is unnecessary, the communication control unit stops transmitting communication data until a predetermined transmission restarting condition is satisfied.