A method for producing a sintered R-T-B based magnet includes applying an adhesive agent to an application area of the magnet, adhering a particle size-adjusted powder of a heavy rare-earth element RH which is at least one of Dy and Tb to the application area, and heating at a temperature which is equal to or lower than a sintering temperature of the magnet to allow the element RH in the particle size-adjusted powder to diffuse from the surface into the interior of the magnet. The particle size of the particle size-adjusted powder is set so that, when powder particles are placed on the entire surface of the magnet to form a single particle layer, the amount of element RH in the particle size-adjusted powder is in a range from 0.6 to 1.5% with respect to the magnet by mass ratio.