A power converter apparatus comprising: a substrate on which a plurality of switching elements are mounted; a plate-like positive interconnection member and a plate-like negative interconnection member, which are arranged to be close to and parallel with each other and are arranged to be parallel with the substrate, while being electrically insulated from each other; a capacitor having a positive terminal electrically connected to the positive interconnection member and a negative terminal electrically connected to the negative interconnection member wherein the positive and negative terminals are located on the same side as the capacitor, a cover arranged over the substrate to encompass the switching elements, the positive interconnection member, the negative interconnection member, and the capacitor, wherein the positive interconnection member and the negative interconnection member each have one or more terminal portions (27a, 28a) that is joined to a circuit pattern (24b, 24c) on the substrate by ultrasonic bonding, wherein the capacitor is arranged on one of the positive and negative interconnection members (27, 28) that does not directly face the substrate, wherein the positive and negative terminals are provided on the capacitor so as to face the interconnection member (27 or 28) on which the capacitor is arranged, wherein the positive interconnection member and the negative interconnection member each have two or more of the terminal portions (27a, 28a) extending from at least one end of the interconnection member (27, 28) in the widthwise direction, and the distal ends of the terminal portions (27a, 28a) are bent to extend parallel with the substrate, thereby forming joint portions (27b, 28b), the joint portions (27b, 28b) being joined to the circuit patterns (24b, 24c) by ultrasonic bonding, and wherein the joint portions of the terminal portions of the positive interconnection member and the joint portions of the terminal portions of the negative interconnection member that are arranged on the same side of the positive and negative interconnection members (27, 28) in the widthwise direction are located on a single straight line. a substrate on which a plurality of switching elements are mounted; a plate-like positive interconnection member and a plate-like negative interconnection member, which are arranged to be close to and parallel with each other and are arranged to be parallel with the substrate, while being electrically insulated from each other; a capacitor having a positive terminal electrically connected to the positive interconnection member and a negative terminal electrically connected to the negative interconnection member wherein the positive and negative terminals are located on the same side as the capacitor, a cover arranged over the substrate to encompass the switching elements, the positive interconnection member, the negative interconnection member, and the capacitor, wherein the positive interconnection member and the negative interconnection member each have one or more terminal portions (27a, 28a) that is joined to a circuit pattern (24b, 24c) on the substrate by ultrasonic bonding, wherein the capacitor is arranged on one of the positive and negative interconnection members (27, 28) that does not directly face the substrate, wherein the positive and negative terminals are provided on the capacitor so as to face the interconnection member (27 or 28) on which the capacitor is arranged, wherein the positive interconnection member and the negative interconnection member each have two or more of the terminal portions (27a, 28a) extending from at least one end of the interconnection member (27, 28) in the widthwise direction, and the distal ends of the terminal portions (27a, 28a) are bent to extend parallel with the substrate, thereby forming joint portions (27b, 28b), the joint portions (27b, 28b) being joined to the circuit patterns (24b, 24c) by ultrasonic bonding, and wherein the joint portions of the terminal portions of the positive interconnection member and the joint portions of the terminal portions of the negative interconnection member that are arranged on the same side of the positive and negative interconnection members (27, 28) in the widthwise direction are located on a single straight line.