The present invention relates to a semiconductor device including a Fin type field effect transistor (FET) having a protrusive semiconductor layer protruding from a substrate plane, a gate electrode formed so as to straddle the protrusive semiconductor layer, a gate insulating film between the gate electrode and the protrusive semiconductor layer, and source and drain regions provided in the protrusive semiconductor layer, wherein the semiconductor device has on a semiconductor substrate an element forming region having a Fin type FET, a trench provided on the semiconductor substrate for separating the element forming region from another element forming region, and an element isolation insulating film in the trench; the element forming region has a shallow substrate flat surface formed by digging to a depth shallower than the bottom surface of the trench and deeper than the upper surface of the semiconductor substrate, a semiconductor raised portion protruding from the substrate flat surface and formed of a part of the semiconductor substrate, and an insulating film on the shallow substrate flat surface; and the protrusive semiconductor layer of the Fin type FET is formed of a portion protruding from the insulating film of the semiconductor raised portion.