In the first main surface 3, a recess 33 for causing the first main surface 3 to be recessed toward the second main surface 4 is formed on both sides of the gate insulating film 31. The recess 33 may be formed in the entire region between the gate insulating film 31 and the protruding portion 18 of the insulating buried object 12 in the device region 6.

The gate electrode 32 is formed of conductive polysilicon. The gate electrode 32 is formed on the gate insulating film 31. A width (gate length) of the gate electrode 32 in the second direction Y may be 0.13 μm or more and 0.3 μm or less.

Referring to FIG. 3, the gate electrode 32 crosses the open end 16 of the trench 11 and reaches the insulating buried object 12. Specifically, the gate electrode 32 includes a main body portion 35 facing the first main surface 3 with the gate insulating film 31 interposed therebetween in the device region 6, and a drawing portion 36 facing the insulating buried object 12 on the outer side of the device region 6.

The main body portion 35 is formed on the gate insulating film 31 in the form of a film extending along the gate insulating film 31. The drawing portion 36 is drawn out from the main body portion 35 onto the protruding portion 18 of the insulating buried object 12.