When a nut housing member is inserted from a first opening portion into a case (terminal housing area) in a semiconductor device, first and second protrusions of the nut housing member slide on and pass through the first and second opening portions. Ultimately, the nut housing member is housed in the case (terminal housing area), with the first protrusion being in contact with a lower end of the second opening portion and the second protrusion being in contact with a lower end of the first opening portion. Even if the nut housing member is not inserted in parallel with the terminal housing area, the forefront does not hit against a first beam. Therefore, the nut housing member is inserted stably and housed reliably in the terminal housing area of the case, and the assemblability of the nut housing member with respect to the case is improved.