A precision surface plate has a hollow casing with a reference plane used as a surface on which either or both of a workpiece and mechanical equipment are placed, a honeycomb structure, which is a collection of substantially identically-shaped enclosed cells disposed inside the casing, and a heat transfer device provided in the honeycomb structure to allow cells of the honeycomb structure to communicate with each other and transfer heat. The precision surface plate further includes casing ventilation openings provided in a wall of the casing to allow cells of the honeycomb structure inside the casing to communicate with the outside of the casing, and a shutter for opening and closing the casing ventilation openings. The heat is transferred effectively between the cells of the honeycomb structure through the heat transfer device.