A laminated bus bar is applied to a main wiring circuit of an electric power converter and connected to a semiconductor module. The laminated bus bar includes insulator plates laminated together, and conductors interposed between the insulator plates. Each conductor includes a connection terminal section led out in accordance with an arrangement of a main circuit terminal on the semiconductor module. A creepage groove is formed on an edge of each of the insulator plates in accordance with a position between the connection terminal sections. The laminated bus bar facilitates elongation of the creepage distance between the connection terminals.