Variations of characteristics of a semiconductor device provided with a power MOSFET having a super junction structure are suppressed, and reliability of the semiconductor device is improved. A trench embedding an insulating film, which constitutes an insulator column therein, is formed in a first main surface of a semiconductor substrate whose crystal plane is a (110) plane. A crystal plane of a side surface of the trench in a short-side direction is a (111) plane, and a p-type diffusion layer constituting a p-column is formed in the above-mentioned side surface.