Each of two opposed bus bars includes a main body portion and a connection terminal portion while the connection terminal portion is formed at the main body portion and serves as a portion to be connected to an electric power line portion of a power device. A surface of the main body portion of one of the bus bars is opposed to a surface of the main body portion of the other one of the bus bars, and the other bus bar and the one bus bar are arranged one after the other in a direction perpendicular to the surface of the main body portion. The connection terminal portions of the one bus bar, the connection terminal portions of the other bus bar are arranged one after the other in a direction along the surface of the main body portion.