In an inverse-stagger MOSFET (1), a gate insulating layer (4) made of amorphous aluminum oxide is so formed as to face a channel layer (5) which serves as the semiconductor layer, and which is made of zinc oxide. With this arrangement, a defect level at an interface between the channel layer (5) and the gate insulating layer (4) is reduced, thereby obtaining performance equivalent to that of a semiconductor apparatus in which all the layered films are crystalline. This technique is applicable to a staggered MOSFET and the like, and has high versatility.