Disclosed are CMOS device and CMOS inverter. The CMOS device includes a substrate having active lines extending in a first direction and defined by a device isolation layer, the substrate being divided into an NMOS area, a PMOS area and a boundary area interposed between the NMOS and the PMOS areas and having the device isolation layer without the active line, a gate line extending in a second direction across the active lines and having a first gate structure on the active line in the first area, a second gate structure on the active line in the second and a third gate structure on the device isolation layer in the third area. The electrical resistance and parasitic capacitance of the third gate structure are smaller than those of the NMOS and the PMOS gate structures. Accordingly, better AC and DC performance of the CMOS device can be obtained.