A CMOS device and a method for fabricating the same, is disclosed, the device including an insulating film formed on a substrate, first and second sapphire patterns formed on the insulating film at fixed intervals, first and second epitaxial semiconductor layers formed on the first and second sapphire patterns, isolating structures formed at edges of the first and second semiconductor layers, respectively, first and second trenches formed down to predetermined depths from surfaces of the first and second semiconductor layers, sidewall spacer structures formed at both sides of the first and second trenches, a gate insulating film formed on a surface of each of the first and second semiconductor layers between the sidewall spacer structures, first and second gate electrodes formed in the first and second trenches respectively on the gate insulating film, first conductivity type impurity regions formed in the first semiconductor layer on both sides of the first gate electrodes, and second conductivity type impurity regions formed in the second semiconductor layer on both sides of the second gate electrodes. The CMOS device exhibits reduced latch-up and hot carrier characteristics, improved device reliability, reduced junction and parasitic capacitances, and improved device performance.