An impeller for a rotary machine comprising: an impeller body made of Al or Al alloy; and a Ni-P-based electroless-plated film that covers surfaces of the impeller body, wherein the Ni-P-based electroless-plated film is formed on the surfaces, the impeller body includes surface portions that are provided so as to have a fixed depth from the surfaces of the impeller body, and a middle portion that is disposed inside the surface portions, the surface portions have a first compressive residual stress, the middle portion does not have the first compressive residual stress, and the surface portions and the middle portion are formed integrally with each other, wherein the first compressive residual stress is imparted to each the surface portions by performing a shot peening treatment on the surfaces of the impeller body using glass beads as projection materials, and then the Ni-P-based electroless-plated film is formed on the surfaces of the impeller body after forming the surface portions having the first compressive residual stress, wherein the impeller body includes a blade inlet-root portion and a blade outlet-root portion, the blade inlet-root portion and the blade outlet-root portion include the surface portions, the first compressive residual stresses is an average and compressive residual stress of the residual stress of the blade inlet-root portion and the residual stress of the blade outlet-root portion, an absolute value of the first compressive residual stress at the surfaces of the impeller body is 300 MPa or more, and the depth of the surface portion from the surface of the impeller body is equal to or larger than 0.2 mm and less than 0.4 mm. an impeller body made of Al or Al alloy; and a Ni-P-based electroless-plated film that covers surfaces of the impeller body, wherein the Ni-P-based electroless-plated film is formed on the surfaces, the impeller body includes surface portions that are provided so as to have a fixed depth from the surfaces of the impeller body, and a middle portion that is disposed inside the surface portions, the surface portions have a first compressive residual stress, the middle portion does not have the first compressive residual stress, and the surface portions and the middle portion are formed integrally with each other, wherein the first compressive residual stress is imparted to each the surface portions by performing a shot peening treatment on the surfaces of the impeller body using glass beads as projection materials, and then the Ni-P-based electroless-plated film is formed on the surfaces of the impeller body after forming the surface portions having the first compressive residual stress, wherein the impeller body includes a blade inlet-root portion and a blade outlet-root portion, the blade inlet-root portion and the blade outlet-root portion include the surface portions, the first compressive residual stresses is an average and compressive residual stress of the residual stress of the blade inlet-root portion and the residual stress of the blade outlet-root portion, an absolute value of the first compressive residual stress at the surfaces of the impeller body is 300 MPa or more, and the depth of the surface portion from the surface of the impeller body is equal to or larger than 0.2 mm and less than 0.4 mm.