Provided is a fission product processing method for selectively transmuting only a long-lived radionuclide from fission products. The method for processing radioactive waste includes the step of extracting, from the radioactive waste, the isotopes without isotope separation, the isotope elements including radionuclides of fission products and having a common atomic number, and the step of irradiating the isotopes with high-energy particles generated by an accelerator to produce nuclear transmutation of a long-lived radionuclide of the radionuclides into a short-lived radionuclide with a short half-life or a stable nuclide re-utilizable as a resource.