PURPOSE: To contrive to manufacture laminate sheet having small warpage dimensional change by reducing strain remaining in the laminated sheet by a method wherein structural material is thermally pressurized under the condition being pinched between end plates, each of which is obtained by piling-up the scribed number of prepregs and thermally pressurizing them.

CONSTITUTION: Laminated sheet used as an end plate preferaly has the flexural elastic modulus of 50-150% of that of the laminates sheet to be manufactured, the linear expansion coefficient of 50-150% of that of the laminated sheet to be manufactured and the glass transition point of ±15°C of that of the laminated sheet to be manufactured. In addition, the above-mentioned physical values in all three directions or the longitudinal, lateral and thickness directions are preferably as near those of the laminated sheet to be manufactured as possible. Accordingly, the base materials and resins of the end plate and of the laminated sheet are most preferably the same as each other. Thus, since the physical values of the end plate approximate those of the laminated sheet to be manufactured, in the changes such as expansion, contraction and the like at the hardening under pressure and heat and cooling of the end plates and laminated sheet to be manufactured, both show behaviours closely equal to each other, resulting in making the degree of restriction of the laminated sheet by the end plates small. Accordingly the residual internal strain is remarkably reduced.