The invention prevents a semiconductor device from warping due to heat when it is used. The invention also prevents a formation defect such as peeling of a resist layer used as a plating mask and a formation defect of a front surface electrode. A source pad electrode connected to a source region is formed on a front surface of a semiconductor substrate forming a vertical MOS transistor. A front surface electrode is formed on the source pad -electrode by a plating method using a resist layer having openings as a mask. The semiconductor substrate formed with the front surface electrode is thinned by back-grinding. A back surface electrode connected to a drain region is formed on the back surface of the semiconductor substrate. The front surface electrode and the back surface electrode are made of metals having the same coefficients of linear expansion, preferably copper. The front surface electrode and the back surface electrode preferably have the same thicknesses or almost the same thicknesses.