Disclosed herein is a CMOS image sensor for improving an image quality by removing an offset noise occurred in a path difference. The CMOS image sensor includes a pixel array including a plurality of a first pixel and a second pixel; a first analog data bus and a second analog data bus for transferring a first pixel data and a second pixel data, each generated from the first pixel and the second pixel; a first analog signal processing unit and a second analog signal processing unit, each for amplifying an inputted pixel data to extract a pure pixel data; and a swapping unit for swapping the first pixel data and the second pixel data to thereby delivery each of first and second swapped pixel data into each of the first and the second analog signal processing unit.