A method of impregnating voids of a sintered metal body having a porous structure with resin, the method comprising preparing a resin material that contains a defoamer containing hydrophilic or hydrophobic particles, defoaming the prepared resin material by reducing pressure of the resin material, applying the defoamed resin material onto a surface of the sintered metal body, impregnating the voids with the resin material by reducing pressure of the sintered metal body and the resin material applied to the surface of the sintered metal body so as to expel gas from the voids; and curing the resin material by heating.