A wide band gap semiconductor device comprising: a drain electrode ; a drift layer being a first conductivity type and provided above the drain electrode ; a well region being a second conductivity type and provided in the drift layer ; a source region being the first conductivity type and provided in the well region and electrically connected to a source pad ; a gate electrode electrically connected to a gate pad ; a gate contact region being the first conductivity type and provided in the well region and electrically connected to the gate pad ; a Zener diode region provided in the well region and provided between the source region and the gate contact region in a plane direction; an interlayer insulating film ; and a gate insulating film provided on the well region and provided between the well region and the interlayer insulating film , wherein the gate electrode is provided on the gate insulating film , characterized in that the Zener diode region has a superhigh-concentration second conductivity type semiconductor region electrically connected to the source pad and a high-concentration first conductivity type semiconductor region adjacent to the superhigh-concentration second conductivity type semiconductor region , the gate contact region is adjacent to the high-concentration first conductivity type semiconductor region , and the superhigh-concentration second conductivity type semiconductor region is provided at a side of the source region closer than the high-concentration first conductivity type semiconductor region ; wherein the high-concentration first conductivity type semiconductor region has an impurity concentration of 1 × 10 18 to 2 × 10 19 cm -3 , and wherein the superhigh-concentration second conductivity type semiconductor region has a higher impurity concentration of 2 × 10 19 to 1 × 10 21 cm -3 . a drain electrode ; a drift layer being a first conductivity type and provided above the drain electrode ; a well region being a second conductivity type and provided in the drift layer ; a source region being the first conductivity type and provided in the well region and electrically connected to a source pad ; a gate electrode electrically connected to a gate pad ; a gate contact region being the first conductivity type and provided in the well region and electrically connected to the gate pad ; a Zener diode region provided in the well region and provided between the source region and the gate contact region in a plane direction; an interlayer insulating film ; and a gate insulating film provided on the well region and provided between the well region and the interlayer insulating film , wherein the gate electrode is provided on the gate insulating film , characterized in that the Zener diode region has a superhigh-concentration second conductivity type semiconductor region electrically connected to the source pad and a high-concentration first conductivity type semiconductor region adjacent to the superhigh-concentration second conductivity type semiconductor region , the gate contact region is adjacent to the high-concentration first conductivity type semiconductor region , and the superhigh-concentration second conductivity type semiconductor region is provided at a side of the source region closer than the high-concentration first conductivity type semiconductor region ; wherein the high-concentration first conductivity type semiconductor region has an impurity concentration of 1 × 10 18 to 2 × 10 19 cm -3 , and wherein the superhigh-concentration second conductivity type semiconductor region has a higher impurity concentration of 2 × 10 19 to 1 × 10 21 cm -3 . <EOS>