A semiconductor device, including a semiconductor module and a conducting board. The semiconductor module includes a semiconductor chip and an external connecting terminal which has a first end electrically connected to the semiconductor chip and a second end extending from the semiconductor chip. The conducting board has a terminal hole penetrating therethrough, an inlet and an outlet of the terminal hole being respectively on two opposite surfaces of the conducting board. The conducting board is electrically connected to the external connecting terminal, of which the second end fits into the terminal hole from the inlet toward the outlet, and is fixed therein by solder. At least one of the terminal hole and the second end of the external connecting terminal has a lock part. The second end of the external connecting terminal, inserted into the terminal hole, is locked by the lock part and thereby remains in the terminal hole.