A power conversion device mounted on a vehicle or the like has functions of converting DC power into AC power and supplying the same to a rotating electrical machine and converting AC power from the rotating electrical machine into DC power. The power conversion device has an inverter circuit constituted by a semiconductor element having a switching function. As a circuit body performing power conversion, that is, a power semiconductor module, one with a structure formed by resin-sealing an upper arm circuit and a lower arm circuit, which are constituted by insulating gate bipolar transistors (IGBTs) and diodes, integrally has been known. In a circuit body with this structure, each of the IGBTs and the diodes of the upper and lower arm circuits is mounted on one face of an insulating board. A metal base is arranged on the other face of a pair of insulating boards on which the upper arm circuit or the lower arm circuit is formed.
The connection conductors connected to the IGBTs and the IGBTs of the upper and lower arm circuits are mounted so as to form a loop current path on the metal base. In this circuit, when the IGBTs of the upper arm circuit are turned on, the diodes of the lower arm circuit are reverse biased so that the recovery current passes through the upper and lower arm circuits. At this time, an induced current is generated at the metal base. The direction of the magnetic flux generated around this induced current is opposite to the direction of the magnetic flux generated by the recovery current flowing through each conductor plate of the upper and lower arm circuits. Thus, the magnetic fluxes cancel each other, and an inductance of an internal circuit decreases (e.g., see FIG. 9 of PTL 1).