An electronic control device has a housing, a circuit board, and a connector. One of surfaces of the housing is formed as a mounting surface. The circuit board including a heat-producing component is fixed to an inner wall of the housing. The connector is electrically connectable with an external device. The mounting surface and the inner wall, to which the circuit board is fixed, are located on opposite sides of the housing. The circuit board and the connector are electrically connected to each other via a flexible connecting member.