An electronic control unit includes a board, a heat-generating device, a connector, and a heatsink. The board has an insulating layer and a wiring pattern partially exposed outside the insulating layer. The heat-generating device is mounted on the board and electrically connected to the wiring pattern. The connector is located adjacent to the heat-generating device and has a connection terminal connected to the wiring pattern. The heatsink is located opposite to the board across the heat-generating device and in contact with the heat-generating device to dissipate heat of the heat-generating device. The wiring pattern has a land pattern including a mount portion and a connection portion. The heat-generating device is mounted on the mount portion. The connection terminal of the connector is connected to the connection portion.