An electronic field reduction in a corner of a trench section of a semiconductor is achieved by forming a p-type base region in a source area of an n-type drain region, and both an n-type source region and a gate leading region are formed in a surface area of the p-type base region separately from each other. A trench section is formed in both the source region and gate leading region to reach the drain region. Polysilicon is formed in the trench section and on the surface of a semiconductor substrate with a gate insulation film interposed therebetween and then thermally treated. An interlayer insulation film is deposited on the entire surface of the semiconductor substrate, and then contact holes reaching the gate leading region and the source and base regions in the peripheral portion of the trench section in the source region are formed. A source/base electrode which contacts both the source and base regions through one of the contact holes is formed. A gate electrode is formed which contacts both the gate leading region and the polysilicon in the trench through the other contact hole.