To provide an image forming apparatus capable of attaining the miniaturization of the product in size while maintaining efficiency in cooling electrical components by radiating by a board supporting member formed of sheet steel in the case of cooling the electrical components, without making an outer cover for covering the electrical part large in size.

The image forming apparatus is provided with a circuit board with the electrical components having a large heat value mounted and a supporting member of the circuit board, wherein the supporting member is constituted of thermal conductive material, and also, the electrical components are arranged near the supporting member, and the supporting member is connected to the electrical components in a thermal conductive state.