A neutron generator is provided to convert a long-life nuclide material into a short-life nuclide material through a nuclear reaction with neutron. A neutron generator includes a nuclear fusion reactor and a nuclear fission reactor. The nuclear fusion reactor generates neutron by a nuclear fusion from a heavy hydrogen gas supplied from outside. The nuclear fission reactor generates a plurality of high flux neutrons by a nuclear fission of the neutron. The nuclear fusion reactor includes a plasma generator, an accelerator, and a nuclear fusion object(11). The plasma generator generates a heavy hydrogen nucleus from the heavy hydrogen gas supplied from outside. The accelerator(10) accelerates the heavy hydrogen nucleus. The nuclear fusion object includes a tritium or a heavy hydrogen. The heavy hydrogen nucleus collides with the nuclear fusion object.
