A load board includes an electronic component and first wiring connected thereto. A power supply board includes a DC/DC converter and second wiring connected thereto. A bus block includes prismatic block-shaped conductors arranged with a gap interposed therebetween and fixed. The bus block is held between the first plate member and the second plate member such that the end faces of the block-shaped conductors are in contact with the load board and the power supply board. The bus block is connected to the first wiring and the second wiring such that current flows in a direction from the power supply board to the load board in one of two adjacent block-shaped conductors and that current flows in a direction from the load board to the power supply board in the other block-shaped conductor.