A semiconductor device comprises: a gate insulating film 190 stacked on a semiconductor layer 130; and a gate electrode layer 230 stacked on the gate insulating film 190 and provided to apply a voltage via the gate insulating film 190 for formation of a channel in the semiconductor layer 130. The gate insulating film 190 includes: a first insulation film 192 stacked on the semiconductor layer 130; and a second insulation film 194 between the first insulation film 192 and the gate electrode layer 230. When ∈1 and ∈2 respectively represent relative permittivities of the first and second insulation film 192, 194, d1 [nm] and d2 [nm] represent film thicknesses of the first and second insulation film 192, 194, and Vmax [V] represents a rated voltage applicable to the gate electrode layer 230, the semiconductor device is configured to satisfy ∈1