An electronic circuit device comprises: a semiconductor element having a first surface and a second surface, with the first and second surfaces being on first and second sides of the semiconductor element, respectively, and facing in opposite directions; a first electrode on the first surface; a second electrode on the second surface; a first circuit board electrically connected to the first electrode via a metallic plate such that the metallic plate and the semiconductor element are on the first circuit board; a second circuit board on the second side of the semiconductor element, the second circuit board having a control circuit for the semiconductor element; and a metallic wire for directly electrically interconnecting the second electrode and the second circuit board.