A semiconductor device comprising: a substrate ; a drift region of a first conductivity type formed on a first main surface of the substrate and having a higher impurity concentration than the substrate ; a well region of a second conductivity type extending in the drift region from a second main surface of the drift region in a direction perpendicular to the second main surface, the second main surface being opposite from a first main surface of the drift region in contact with the substrate ; a source region of the first conductivity type extending in the well region from the second main surface in the perpendicular direction; a gate groove formed from the second main surface in the perpendicular direction and extending in contact with the source region , the well region in a direction parallel to the second main surface, and the drift region ; a drain region of the first conductivity type formed away from the well region in the drift region and extending from the second main surface in the perpendicular direction; a gate insulating film formed on a surface of the gate groove ; a gate electrode formed on a surface of the gate insulating film ; a source electrode electrically connected to the source region and the well region ; a drain electrode electrically connected to the drain region ; a protection region of the second conductivity type formed in the drift region , on a surface of the gate insulating film facing the drain region ; and a connection region of the second conductivity type formed in the drift region while being in contact with the well region and the protection region , wherein the well region and the protection region are electrically connected to each other by the connection region , and the protection region is in contact with an entire end surface of the gate groove facing the drain region . a substrate ; a drift region of a first conductivity type formed on a first main surface of the substrate and having a higher impurity concentration than the substrate ; a well region of a second conductivity type extending in the drift region from a second main surface of the drift region in a direction perpendicular to the second main surface, the second main surface being opposite from a first main surface of the drift region in contact with the substrate ; a source region of the first conductivity type extending in the well region from the second main surface in the perpendicular direction; a gate groove formed from the second main surface in the perpendicular direction and extending in contact with the source region , the well region in a direction parallel to the second main surface, and the drift region ; a drain region of the first conductivity type formed away from the well region in the drift region and extending from the second main surface in the perpendicular direction; a gate insulating film formed on a surface of the gate groove ; a gate electrode formed on a surface of the gate insulating film ; a source electrode electrically connected to the source region and the well region ; a drain electrode electrically connected to the drain region ; a protection region of the second conductivity type formed in the drift region , on a surface of the gate insulating film facing the drain region ; and a connection region of the second conductivity type formed in the drift region while being in contact with the well region and the protection region , wherein the well region and the protection region are electrically connected to each other by the connection region , and the protection region is in contact with an entire end surface of the gate groove facing the drain region . <EOS>