A power semiconductor module available under environments of high temperature has enhanced heat resistance of silicone gel filled up in a case. A power semiconductor module comprises a power semiconductor element, an insulating substrate mounted with the power semiconductor element, a resin case containing the power semiconductor element and the insulating substrate, a silicone gel injected into the resin case, and a sheet composed of a silicone rubber or silicone resin, disposed between the resin case and the silicone gel within the resin case.