A base plate (1) made of a metal has a through-hole (2). An insulating substrate (3) is provided on the base plate (1). A semiconductor chip (4) is provided on the insulating substrate (3). A case (8) has a screw-hole (9) communicating with the through-hole (2), covers the insulating substrate (3) and the semiconductor chip (4), and is disposed on the base plate (1). A screw (11) made of a metal is inserted into the through-hole (2) and the screw-hole (9) to fix the case (8) to the base plate (1). A flexible material (12) having flexibility is filled in a cavity between a bottom surface of the screw-hole (9) in the case (8) and a distal end of the screw (11).