A resin molding die has a molding surface formed of a low adhesion material formed of a solid solution of La—Y2O3 produced from Y2O3 and an other oxide of La2O3. La2O3 contains La, which has an ionic radius larger than Y3+, and is larger in basicity than Y2O3. The low adhesion material contains La2O3 at a predetermined ratio relative to a total of Y2O3 and La2O3. The low adhesion material thus has a large iconic radius contributing to a smaller number of sites per unit area than Y2O3, a larger basicity contributing to a smaller force binding the low adhesion material with a basic substance than Y2O3, and a ratio contributing to shape retention. The low adhesion material thus less adhesive and more shape-retentive than Y2O3 configures the molding surface. A low adhesion material that is less adhesive to a basic substance than Y2O3 is and excellently shape-retentive, and an excellently releasable and shape-retentive resin molding die can thus be obtained.