Power conversion device

A power conversion device, comprising:

• a main circuit which has:
• a first wiring layer and a second wiring layer that are formed respectively on both surfaces of a base board;
• mounted parts that are mounted on the first wiring layer and the second wiring layer, said mounted parts including a mounted part which forms a circuit having an inductance component as a limped constant and mounted parts which form each a circuit other than a circuit having an inductance component as a lumped constant;
• and a first GND layer and a second GND layer that are formed respectively, between the external-layer portions and the internal-layer portion of the base board and in regions corresponding to the mounted parts which form each a circuit other than a circuit having an inductance component as a lumped constant, and to the first wiring layer and the second wiring layer;
• and
• a cooler which is attached to the base board by means of a fixing screw through a first through-hole created in an end portion of that board;
• wherein the first GND layer and the second GND layer are each formed so that a creepage distance is created around a second through-hole in which a lead of one of the mounted parts which form each cha circuit other than a circuit having an inductance component as a lumped constant, that connects the first wiring layer and the second wiring layer to each other, is inserted.