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An R-T-B system permanent magnet 1 comprises a magnet body 2 comprising a sintered body comprising at least a main phase comprising R2T14B grains (wherein R represents one or more rare earth elements, and T represents one or more transition metal elements including Fe or Fe and Co essentially) and a grain boundary phase containing R in a larger amount than the main phase, the magnet body 2 having a 300 µm or less thick (not inclusive of zero thick) hydrogen-rich layer 21 having a hydrogen concentration of 300 ppm or more formed in the surface layer portion, and an overcoat 3 covering the surface of the magnet body 2 can improve the corrosion resistance of the R-T-B system permanent magnet 1 with an overcoat 3 formed thereon without degrading the magnetic properties thereof.