A power semiconductor device, comprising: a first semiconductor layer of a first conductivity type; a second semiconductor layer of a second conductivity type, provided on a top side of the first semiconductor layer; a third semiconductor layer of the second conductivity type, provided on the second semiconductor layer; a first semiconductor region of the first conductivity type, provided selectively in a top side of the third semiconductor layer; a second semiconductor region of the second conductivity type, provided selectively in a top side of the first semiconductor region; a gate insulation film provided on the third semiconductor layer, on the first semiconductor region, and partially on the second semiconductor region; a gate electrode including a polysilicon film provided on the gate insulation film, and a doped polysilicon film that is provided on the polysilicon film and doped with impurities; a first main electrode that is provided on the first semiconductor region and is electrically connected with the second semiconductor region; a second main electrode provided on a bottom side of the first semiconductor layer; said polysilicon film provided on the gate insulation film being not doped with impurities, wherein the doped polysilicon film has a concentration gradient along its whole thickness with respect to the impurities in its thickness direction and the concentration gradient gives a highest concentration of the impurities at the top portion of the doped polysilicon film and gives a lowest concentration of the impurities at the bottom portion of the doped polysilicon film, wherein a value of the concentration of the impurities becomes smaller heading thickness-wise toward the polysilicon film. a first semiconductor layer of a first conductivity type; a second semiconductor layer of a second conductivity type, provided on a top side of the first semiconductor layer; a third semiconductor layer of the second conductivity type, provided on the second semiconductor layer; a first semiconductor region of the first conductivity type, provided selectively in a top side of the third semiconductor layer; a second semiconductor region of the second conductivity type, provided selectively in a top side of the first semiconductor region; a gate insulation film provided on the third semiconductor layer, on the first semiconductor region, and partially on the second semiconductor region; a gate electrode including a polysilicon film provided on the gate insulation film, and a doped polysilicon film that is provided on the polysilicon film and doped with impurities; a first main electrode that is provided on the first semiconductor region and is electrically connected with the second semiconductor region; a second main electrode provided on a bottom side of the first semiconductor layer; said polysilicon film provided on the gate insulation film being not doped with impurities, wherein the doped polysilicon film has a concentration gradient along its whole thickness with respect to the impurities in its thickness direction and the concentration gradient gives a highest concentration of the impurities at the top portion of the doped polysilicon film and gives a lowest concentration of the impurities at the bottom portion of the doped polysilicon film, wherein a value of the concentration of the impurities becomes smaller heading thickness-wise toward the polysilicon film.