Abstract: A lateral insulating gate type field effect transistor can be manufactured with ease reliably by using a semiconductor substrate having excellent crystal property. A projected portion (2) is formed on a first major surface side of a semiconductor substrate (1). A first gate portion (3) having a width (length) smaller than that of the projected portion (2) is formed on the projected portion (2). An insulating layer (4) is formed on the whole surface of the semiconductor substrate (1) so as to bury the first gate portion (3). The semiconductor substrate (1) is removed horizontally from its second major surface side, i.e., from the opposite side of the side of the projected portion (2) to a position (a) at which the insulating layer (4) is formed so as to bury the projected portion (2) is exposed. A second gate portion (5) is formed on such exposed surface.