An insulating member includes a fixed charge. The insulating member includes a first insulating part. The first insulating part includes a first region, a second region, and a third region. The first region is positioned between a gate electrode and the second region in a first direction. The second region is positioned between the first region and the third region in the first direction. The third region is positioned between the second region and a second surface in the first direction. A density of the fixed charge is greater in the first region than in the second region.