A method of producing a semiconductor epitaxial wafer is provided. The method includes irradiating a surface of a semiconductor wafer with cluster ions to form a modified layer in a surface portion of the semiconductor wafer, in which the modified layer includes a constituent element of the cluster ions in solid solution. The method further includes forming an epitaxial layer on the modified layer of the semiconductor wafer. The irradiating is performed such that a portion of the modified layer in a thickness direction becomes an amorphous layer, and an average depth of an amorphous layer surface from a semiconductor wafer surface-side of the amorphous layer is at least 20 nm from the surface of the semiconductor wafer.