A power converter apparatus that includes a substrate, plate-like positive and negative interconnection members, capacitors, and a cover is disclosed. Pairs of groups of switching elements are mounted on the substrate. The cover is arranged over the substrate to encompass the switching elements, the positive interconnection member, the negative interconnection member, and the capacitor. The positive interconnection member and the negative interconnection member each have a terminal portion that is joined to a circuit pattern on the substrate by ultrasonic bonding.