PURPOSE: To lower the cost of an auxiliary material for polishing the surface of a semiconductor wafer, a metal plate or the like and heighten the wear resistance of the material, by utilizing the advantages of a laminated polyimide plate as the material and using a fiber-reinforced epoxy resin laminated plate or a prepreg as an intermediate layer.

CONSTITUTION: A prepreg, which is made by coating or impregnating a woven carbon fiber fabric with a thermosetting resin composition containing a thermosetting polyimide resin monomer of prepolymer as an indispensable constituent, is placed on one or both sides of a fiber-reinforced epoxy resin laminated plate or a prepreg. A die-separating film or sheet is then placed on the former prepreg. These materials are interposed between the very smooth surfaces of plates. The materials are laminated together under pressure of 0.1W500kg/cm2 at a temperature of 150W350°C, thereby providing a laminated plate of low cost and high wear resistance as an auxiliary material for polishing.