An n-type first base layer is formed on a semiconductor substrate 1 having a first major surface and a second major surface, and a p-type second base layer is formed thereon. Between the first base layer and the second base layer, a carrier stored layer is formed. The carrier stored layer has a high-concentration impurity layer and a low concentration impurity layer, and the high-concentration impurity layer has a thickness of 1.5 .mu.m or more and an impurity concentration therethrough is made to be 1.0.times.10.sup.16 cm.sup.-3 or more throughout the layer.