A power semiconductor device includes: a first semiconductor layer; second and third semiconductor layers above and alternatively arranged along a direction parallel to an upper surface of the first semiconductor layer; and plural fourth semiconductor layers provided on some of immediately upper regions of the third semiconductor layer. An array period of the fourth semiconductor layers is larger than that of the second semiconductor layer. A thickness of part of the gate insulating film in an immediate upper region of a central portion between the fourth semiconductor layers is thicker than a thickness of part of the gate insulating film in an immediate upper region of the fourth semiconductor layers. Sheet impurity concentrations of the second and third semiconductor layers in the central portion are higher than a sheet impurity concentration of the third semiconductor layer in an immediately lower region of the fourth semiconductor layers.