A semiconductor device may include a first active fin, a second active fin and a gate structure. The first active fin may extend in a first direction on a substrate and may include a first straight line extension portion, a second straight line extension portion, and a bent portion between the first and second straight line extension portions. The second active fin may extend in the first direction on the substrate. The gate structure may extend in a second direction perpendicular to the first direction on the substrate. The gate structure may cross one of the first and second straight line extension portions of the first active fin and may cross the second active fin.