A semiconductor device with a fin structure according to one embodiment of the present invention includes: a fin of a predetermined height formed on an insulating layer of a substrate; a gate electrode formed on both sides of the fin through a gate insulating film; and a source/drain region formed in the fin on both sides of the gate electrode by implanting impurities into the fin; wherein a concentration of the impurities forming the source/drain region in a vicinity of an interface between the fin and the insulating layer in the fin is lower than a concentration of the impurities in a vicinity of the interface between the fin and the insulating layer in the insulating layer.