PURPOSE: To produce a thin laminated plate material of high quality by superposing a backing material coated with an adhesive on the bonding tape bonded surface of spliced thin veneer to bond the same to the spliced thin veneer under heating and pressure.

CONSTITUTION: Spliced thin veneer 4 formed by respectively bonding the abutted ends 2 of thin veneers 1 by a bonding tape 3 and a backing material 5 are laminated by the thermal adhesive applied to the backing material 5 and held to a non-flow state to prevent the penetration of the adhesive into the surface of the spliced thin veneer 4. By the use of the backing material 5 obtained by holding a liquid impermeable membrane between two nonwoven fabrics, the penetration of the adhesive into the rear of the backing material 5 is prevented and, by holding the bonding tape 3 between the spliced thin veneer 4 and the backing material 5, the grinding cost required in the grinding of the surface of the spliced thin veneer 4 is reduced and the thickness of the thin veneer 1 is reduced to reduce the thickness of a laminated thin plate material A.