Prepared is an n− type semiconductor substrate 1 having a first principal surface 1a and a second principal surface 1b opposed to each other, and having a p+ type semiconductor region 3 formed on the first principal surface 1a side. At least a region opposed to the p+ type semiconductor region 3 in the second principal surface 1b of the n− type semiconductor substrate 1 is irradiated with a pulsed laser beam to form an irregular asperity 10. After formation of the irregular asperity 10, an accumulation layer 11 with an impurity concentration higher than that of the n− type semiconductor substrate 1 is formed on the second principal surface 1b side of the n− type semiconductor substrate 1. After formation of the accumulation layer 11, the n− type semiconductor substrate 1 is subjected to a thermal treatment.