A semiconductor device comprising a substrate in which a first region and a second region are defined, a gate line which extends in a first direction and traverses the first region and the second region, a source region including a portion formed in the first region, a first part of a body region which is formed under the portion of the source region in the first region and has a first width, a first well which is formed under the first part of the body region in the first region and has a second width greater than the first width, a second part of the body region which is formed in the second region and has a third width, and a second well which is formed under the second part of the body region in the second region and has a fourth width smaller than the third width.