A semiconductor device includes a semiconductor mounting substrate, a mother case having an opening and housing the semiconductor mounting substrate, a plurality of securing members provided along a rim of the mother case, a screw terminal, and a lid member. The screw terminal has a flat plate portion, an insertion portion extending from the flat plate portion, and a terminal bottom portion, is secured to the securing members by insertion of the insertion portion between adjacent securing members, and is electrically connected to the semiconductor mounting substrate on the terminal bottom portion side. The lid member closes the opening with the screw terminal secured to the securing members. The screw terminal is bent such that the flat plate portion faces an upper surface of the lid member closing the opening. The semiconductor device that can achieve reduction in size of the entire device is obtained.