An electronic heat-dissipating substrate including: lead frames of wiring pattern shapes on a conductor plate; and an insulating member between the lead frames. A plate surface of the lead frames and a top surface of the insulating member form one continuous surface. The part arrangement surface is on both surfaces of the electronic part mounting heat-dissipating substrate, a reductant circuit which includes at least similar dual-system circuit is formed on the electronic part mounting heat-dissipating substrate, a first-system circuit of the dual-system circuit is formed on a first surface of the electronic part mounting heat-dissipating substrate, a second-system circuit of the dual-system circuit is formed on a second surface of the electronic part mounting heat-dissipating substrate, and the common lead frames used in a portion of a circuit wiring are used to the first surface and the second surface of the electronic part mounting heat-dissipating substrate.