Semiconductor integrated circuit devices

A semiconductor integrated circuit device may include a standard cell region on a surface of a substrate and a first active region on the surface of the substrate in the standard cell region, wherein the first active region has a length in a first direction. A second active region may be on the surface of the substrate in the standard cell region, the second active region may have a length in the first direction, the length of the second active region may be greater than the length of the first active region, and an axis in a second direction may intersect centers of the first and second active regions so that the first and second active regions are symmetric about the axis in the second direction. A first gate electrode may extend across the first active region in the first direction, and a second gate electrode may extend across the second active region in the first direction.