A semiconductor device includes a substrate including a fin-shaped active region that protrudes from the substrate, a gate insulating film covering a top surface and both side walls of the fin-shaped active region, a gate electrode on the top surface and the both side walls of the fin-shaped active region and covering the gate insulating film, one pair of insulating spacers on both side walls of the gate electrode, one pair of source/drain region on the fin-shaped active region and located on both sides of the gate electrode, and a lower buffer layer between the fin-shaped active region the source/drain region. The source/drain regions include a compound semiconductor material including atoms from different groups. The lower buffer layer includes a compound semiconductor material that is amorphous and includes atoms from different groups.