An image forming apparatus including a first circuit substrate, a second circuit substrate, a first supporting member for supporting the first circuit substrate, a second supporting member for supporting the second circuit substrate, a holding member for holding the first supporting member and the second supporting member, and a connector for cablelessly connecting the first circuit substrate and the second circuit substrate together, wherein at least one of the first supporting member and the second supporting member is movable in a direction in which the connection by the connector is released, and the first supporting member and the second supporting member are mountable to and dismountable from the holding member independently of each other.