A disclosed communication device performs bidirectional serial communication by using a clock line and a data line. The communication device includes a starting condition detecting unit configured to detect a communication starting condition based on levels of the clock line and the data line and generate, in response to detecting the communication starting condition, a wake up signal for waking up another circuit in the communication device from a standby status; a clock sending/receiving unit connected to the clock line and configured to send/receive a clock signal; and an output control unit configured to fix the clock line at a predetermined level by using the clock sending/receiving unit so as to suspend the bidirectional serial communication after the wake up signal is received from the starting condition detecting unit and until a standby status cancel instruction indicating that the other circuit has woken up from the standby status is received from the other circuit. The bidirectional serial communication is performed with another communication device via the clock line and the data line after the other circuit has woken up.