A power conversion device includes: semiconductor switching elements; a housing on which the semiconductor switching elements are fixed; a circuit board on which a driving circuit for driving the semiconductor switching elements is mounted and which is located opposite to and spaced apart from a fixing surface; insertion guides which are disposed on an opposing surface of the circuit board relative to the fixing surface; and elongated terminal extension members each having a length that is matched with a height of a pulse transformer, one ends of which are bonded to respective lead terminals, and the other ends of which extend toward the insertion guides; wherein the pulse transformer is disposed on the opposing surface so as to be opposite to major surfaces of the semiconductor switching elements.