The present invention provides an R-T-B based sintered magnet having excellent corrosion resistance together with good magnetic properties. The R-T-B based sintered magnet contains R2T14B crystal grains, wherein, an R—Ga—Co—Cu—N concentrated part exists in a grain boundary formed between or among two or more adjacent R2T14B crystal grains, and the concentrations of R, Ga, Co, Cu and N in the R—Ga—Co—Cu—N concentrated part are higher than those in the R2T14B crystal grains respectively.