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 adventages of a laminated polyimide plate as the material and using a metal plate 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 or prepolymer as an indispensable constituent, is placed on one or both sides of a metal plate. A die-separating film or sheet is then placed on the prepreg. These materials are interposed between the very smooth surfaces of plates and laminated together under pressure of 0.1W 500kg/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.