An organic compound having an affinity for a resin of a molded resin article and sublimation properties is allowed to penetrate/disperse into the surface of the molded resin article, thereby modifying and/or coloring a resin surface layer. The molded resin article and the organic compound having the affinity for the resin and the sublimation properties are put into a tightly closable container, and the pressure and the temperature in the container are adjusted to place them in a saturated sublimation pressure state of the organic compound, whereby a vapor of the organic compound is uniformly deposited on the surface of the molded resin article and it further penetrates/disperses into the resin surface layer, and in consequence, the resin surface layer can be modified and/or colored. In addition, the modification of the resin surface layer permits imparting a function thereto.