A mold surface (6) of an upper mold (1) with which a fluid resin comes into contact has an oxide (3) therein. The oxide (3) contains a metal cation and an ion. Field strength is calculated based on a valence of the metal cation and an ionic radius of the ion. Based on predetermined relationship established between a value of the field strength and adhesion strength between a cured resin and the mold surface (6), releasability between the cured resin and the mold surface (6) is evaluated. Thereby, a method of evaluating releasability between the cured resin and the mold surface (6) is established. With this evaluation method, a material with high releasability (3) can readily be provided. Further, if the material with high releasability (3) is used for the mold surface (6) of the upper mold (1), a mold for molding a resin having excellent releasability can be obtained.
