PURPOSE: To prevent a plurality of pellets from being heated to high temperature by mounting the pellets on a supporting plate made of a material having a good thermal conductivity when standing the pellets on a circuit board.

CONSTITUTION: In a semiconductor device 1, a plurality of supporting plates 3 are stood substantially perpendicularly to a circuit board with solder 4a on a circuit board 2, pellets 5 are mounted on both side surfaces of the plates 3 with the back surfaces disposed at the plates 3 side with solder 4b, and electrodes 6 provided near the board 2 on the surface of the pellets 5 and electrodes 7 formed on the board 2 are electrically connected by solder balls 8. The solders 4a, 4b are formed of gold-silicon eutectic crystal. The plates 3 are formed of silicon carbide. Since the heats generated at the pellets 5 are efficiently dissipated externally efficiently by heat sink fins 10 through the board 2, the high heating of the pellets 5 can be prevented.