A precision surface plate comprising: a hollow casing having 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 almost 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; heat being transferred effectively between the cells of the honeycomb structure through the heat transfer device.