According to the present invention, capacitors are mounted at the center portion of a printed board, and semiconductor devices are mounted at both sides of the printed board. A heat sink is formed of a first heat sink having a shape with short fins and long fins according to the outer shapes of the capacitors, and a second heat sink having a shape which is the same as that of the first heat sink, wherein the fins of both heat sinks are inwardly provided to face each other. A heat radiating sheet for radiating heat is provided between the heat sink and the semiconductor devices. With this configuration, a stack heat-radiating structure and a power conversion device provided with a stack having the stack heat-radiating structure can be provided which suppress temperature increase in the capacitors and the heat sinks and enable downsizing of the stack.