A semiconductor device includes a substrate having an active region, a first group of standard cells arranged in a first row on the active region of the substrate and having a first height defined in a column direction, a second group of standard cells arranged in a second row on the active region of the substrate, and having a second height, and a plurality of power lines extending in a row direction and respectively extending along boundaries of the first and the second groups of standard cells. The first and second groups of standard cells each further include a plurality of wiring lines extending in the row direction and arranged in the column direction, and at least some of wiring lines in at least one standard cell of the first and second groups of standard cells are arranged at different spacings and/or pitches.