A power
semiconductor module according to the present invention includes: a planar base plate having a plurality of insulated substrates soldered on the top surface, the insulated substrates each having power
semiconductor elements to be cooled mounted thereon; a plurality of
radiation fins projecting from the bottom surface side of the base plate; and a
peripheral wall projecting from the bottom surface side of the base plate so as to surround the
radiation fins, the projecting length of the
radiation fins is less than or equal to that of the
peripheral wall, and the
peripheral wall has end surfaces present in the same plane. In addition, a
power semiconductor device having the power
semiconductor module mounted therein includes: at least one reinforcing plate disposed on the top surface side of the base plate via a first buffering member; and a cooling jacket fixed to the bottom surface side of the base plate via a second buffering member with a plurality of tightening fixtures passing through the reinforcing plate and the base plate, the cooling jacket having a flow passage for a
cooling medium formed to intervene in a position with respect to the base plate, and the first buffering member and the second buffering member are respectively disposed at least inside and outside with respect to the tightening fixtures.