Relay unit

A relay unit comprising:

• a first busbar forming at least a part of an electric current path between a connecting portion, which is connected to a charging connector of an external charging device, and an in-vehicle battery;
• a relay device provided on the first busbar and closed when the in-vehicle battery is charged by the external charging device;
• a second busbar forming at least a part of an electric current path between the in-vehicle battery and a power conversion device, which is for driving a traveling motor;
• and
• a heat dissipation structure, wherein
• the first busbar is branched at a branch portion from the second busbar, and includes at least a part of an electric current path extending from the branch portion to the connection portion via the relay device, and
• the heat dissipation structure dissipates the heat from at least a part of the first busbar between the branch portion and the relay device.