The semiconductor device includes an active region, a recess, a Fin channel region, a gate insulating film, and a gate electrode. The active region is defined by a device isolation structure formed in a semiconductor substrate. The recess is formed by etching the active region and its neighboring device isolation structure using an island shaped recess gate mask as an etching mask. The Fin channel region is formed on the semiconductor substrate at a lower part of the recess. The gate insulating film is formed over the active region including the Fin channel region and the recess. The gate electrode is formed over the gate insulating film to fill up the Fin channel region and the recess.