A method of manufacturing a semiconductor device that includes a semiconductor layer of a first conductivity type, and a parallel pn layer formed on the semiconductor layer, the pn layer having first semiconductor regions of the first conductivity type and second semiconductor regions of a second conductivity type, the first and second regions being alternately arranged parallel to a surface of the semiconductor layer. In one embodiment, the method includes repeatedly performing the following steps to stack the epitaxial growth layers on the semiconductor layer to form the pn layer: forming an epitaxial growth layer of the first conductivity type or non-doped, the epitaxial growth layer having an impurity concentration lower than that of the semiconductor layer, ion implanting a first-conductivity-type impurity into the epitaxial growth layer, selectively ion implanting a second-conductivity-type impurity into the epitaxial growth layer and ion implanting a group 18 element into the epitaxial growth layer.