A semiconductor device including a substrate including a division region extending in a first direction, first and second active patterns on the substrate with the division region interposed therebetween, the first and the second active patterns being spaced apart from each other in a second direction perpendicular to the first direction, gate electrodes extending in the first direction and crossing the first and second active patterns, a first channel pattern on the first active pattern, and a second channel pattern on the second active pattern may be provided. The smallest width of the first active pattern may be smaller than the smallest width of the second active pattern, in the first direction. An end portion of the first channel pattern adjacent to the division region may include a protruding portion extending in the first direction, and the protruding portion may have a triangle shape in a plan view.