To change setting of a transceiver by a simple configuration in a communication unit including a communication device which performs communication through a communication terminal connectable to a communication line.

In a communication unit 60, a GWECU 10 has an ECU side connector 45 capable of mounting a connection connector for connecting communication terminals 32-34 to a bus A5, a bus B6, and a bus C7, and performs communication through the communication terminals 32-34 when the bus A5, the bus B6, and the bus C7 are connected to the communication terminals 32-34. A vehicle side connector 50 has a short-circuit part 55 for fixing the potential of the communication terminal 34 at a prescribed potential without connecting the communication terminal 34 to a communication line such as the bus C7, and can be mounted to the ECU side connector 45.