WIRE HARNESS AND COMMUNICATION RELAY METHOD

Provided are a wire harness and a communication relay method with which effects such as reduction in the relay processing load of an in-vehicle device or improvement in the scalability of an in-vehicle device can be expected. A wire harness according to an embodiment includes a circuit board detachably mountable to an in-vehicle device, a plurality of communication lines connected to the circuit board, and a relay unit provided on the circuit board and configured to relay communication between the plurality of communication lines and to relay communication between the communication lines and the in-vehicle device.