A semiconductor device including a CMOS process-based Hall sensor is provided. The semiconductor device which may include a N-type sensing region which is formed on a semiconductor substrate; P-type contact regions and N-type contact regions which are alternately formed in the N-type sensing region; a plurality of first trenches which are formed in contact with the P-type contact regions and have a first width; and a plurality of second trenches which separate the P-type contact regions and the N-type contact regions and have a second width less than the first width.