A semiconductor unit includes a first conductive layer, a second conductive layer electrically insulated from the first conductive layer, a first semiconductor device mounted on the first conductive layer, a second semiconductor device mounted on the second conductive layer, a first bus bar for electrical connection of the second semiconductor device to the first conductive layer, and a second bus bar for electrical connection of the first semiconductor device to one of the positive and negative terminals of a battery. The first bus bar is disposed in overlapping relation to the second bus bar in such a manner that mold resin fills between the first bus bar and the second bus bar.