A semiconductor device including a semiconductor substrate having on its surface a recess and at least one projection formed in the recess. The projection has a channel region and an element isolating insulating film is formed in the recess. A MIS type semiconductor element is formed on the semiconductor substrate and includes a gate electrode formed on the channel region of the projection via a gate insulating film. Source and drain regions are formed to pinch the channel region of the projection therebetween. A channel region of the MIS type semiconductor element is formed to reach the at least one projection located adjacent to the MIS type semiconductor element in its channel width direction via the recess. A top surface of the at least one projection is located higher than the top surface of the element isolating insulating film by 20 nm or more.