A manufacturing method of an electric power semiconductor device includes following processes. A plurality of first second conductivity type impurity implantation layers are formed in a surface of a second semiconductor layer of a first conductivity type. A first trench is formed between a first non-implantation region and one of the plurality of first second conductivity type impurity implantation layers. An epitaxial layer of the first conductivity type is formed and covers the plurality of first second conductivity type impurity implantation layers. A plurality of second second conductivity type impurity implantation layers are formed in a surface of the epitaxial layer. A second trench is formed between a second non-implantation region and one of the plurality of second second conductivity type impurity implantation layers. A third semiconductor layer of the first conductivity type is formed and covers the plurality of second second conductivity type impurity implantation layers.