A method of manufacturing a semiconductor device, comprising: depositing a hetero semiconductor region on a first conductive-type semiconductor substrate, wherein the hetero semiconductor region forms a heterojunction with the semiconductor substrate; forming a trench wherein a bottom portion of the trench extends into the semiconductor substrate and a thickness of a portion of the hetero semiconductor region around the trench is smaller than a thickness of other portions of the hetero semiconductor region, wherein forming the trench includes selectively removing the semiconductor substrate and the hetero semiconductor region by an anisotropic etching using a mask pattern having an edge portion (31 a) in a taper form obtained by an isotropic etching, thereby transferring the taper form of the mask pattern into the hetero semiconductor region; forming a sacrificial oxide film by thermally oxidizing at least the hetero semiconductor region after forming the trench; selectively removing the portion of the hetero semiconductor region around the trench having a thickness smaller than the thickness of the other portions by removing the sacrificial oxide film thereby receding the hetero semiconductor region from a side wall of the trench in the semiconductor substrate; forming the gate insulating film on the semiconductor substrate and the hetero semiconductor region including an inner surface of the trench after removing the sacrificial oxide film; forming a gate electrode adjacent to a junction end of the semiconductor substrate and the hetero semiconductor region using the gate insulating film; forming a source electrode connected to the hetero semiconductor region; and forming a drain electrode connected to the semiconductor substrate, wherein a driving point of the semiconductor device, where the gate insulating film, the hetero semiconductor region and the semiconductor substrate are adjoined, is at a position spaced apart from a side wall of the trench in the semiconductor substrate. depositing a hetero semiconductor region on a first conductive-type semiconductor substrate, wherein the hetero semiconductor region forms a heterojunction with the semiconductor substrate; forming a trench wherein a bottom portion of the trench extends into the semiconductor substrate and a thickness of a portion of the hetero semiconductor region around the trench is smaller than a thickness of other portions of the hetero semiconductor region, wherein forming the trench includes selectively removing the semiconductor substrate and the hetero semiconductor region by an anisotropic etching using a mask pattern having an edge portion (31 a) in a taper form obtained by an isotropic etching, thereby transferring the taper form of the mask pattern into the hetero semiconductor region; forming a sacrificial oxide film by thermally oxidizing at least the hetero semiconductor region after forming the trench; selectively removing the portion of the hetero semiconductor region around the trench having a thickness smaller than the thickness of the other portions by removing the sacrificial oxide film thereby receding the hetero semiconductor region from a side wall of the trench in the semiconductor substrate; forming the gate insulating film on the semiconductor substrate and the hetero semiconductor region including an inner surface of the trench after removing the sacrificial oxide film; forming a gate electrode adjacent to a junction end of the semiconductor substrate and the hetero semiconductor region using the gate insulating film; forming a source electrode connected to the hetero semiconductor region; and forming a drain electrode connected to the semiconductor substrate, wherein a driving point of the semiconductor device, where the gate insulating film, the hetero semiconductor region and the semiconductor substrate are adjoined, is at a position spaced apart from a side wall of the trench in the semiconductor substrate.