A semiconductor device including a well region in a substrate, an impurity region in the well region, a first active fin on the impurity region, a second active fin on the well region, and a connection pattern penetrating the second active fin and connected to the well region may be provided. The substrate and the impurity region include impurities having a first conductivity type. The well region includes impurities having a second conductivity type different from the first conductivity type. The first active fin includes a plurality of first semiconductor patterns that are spaced apart from each other in a direction perpendicular to a top surface of the substrate. The first semiconductor patterns and the impurity region include impurities having the first conductivity type.