A semiconductor device includes a semiconductor substrate including a main surface, a plurality of first projecting portions which include portions of the semiconductor substrate provided in a first region of the semiconductor substrate to extend in a first direction along the main surface of the semiconductor substrate and to be spaced apart from each other in a second direction, orthogonal to the first direction, along the main surface of the semiconductor substrate, a first isolation region provided between the first projecting portions adjacent to each other, and first and second transistors provided in and over an upper part of each of the first projecting portions which is exposed from an upper surface of the first isolation region to be adjacent to each other in the first direction.