A method for manufacturing a rare earth permanent magnet includes manufacturing an NdFeB sintered magnet. A grain boundary diffusion material in the form of a mixed powder comprising an alloy powder containing Re1aMb or M; and Re2 hydride or Re2 fluoride is disposed on a surface of the NdFeB sintered magnet. The grain boundary diffusion material is heated to diffuse at least one of Re1, Re2 and M into a grain boundary part inside the sintered magnet or a grain boundary part region of a sintered magnet main phase grain. Re1 and Re2 are each rare earth elements selected from the group consisting of dysprosium, terbium, neodymium, praseodymium, and holmium, M is a metal compound consisting of copper, zinc, tin, and aluminum, 0.1