PURPOSE: To bond a decorative sheet to a base board so as to coincide with the grooves thereof regardless of the depth or shape thereof, by imparting folds synchronous to the grooves of the base board to the decorative sheet before bonding and laminating said sheet to the base board under pressure if necessary while applying heat thereto.

CONSTITUTION: A long decorative sheet 3 coated with a heat-sensitive adhesive 31 is delivered from a reel 6 and folds 5 synchronous to the grooves 2 of a base board 1 are applied to said sheet using convex and concave rollers 8A, 9A and 8B, 9B having the shapes corresponding to the grooves 2 of the board 1. The surface of the heat- sensitive adhesive 31 of the decorative sheet 3 having the folds 5 applied thereto is superposed on the base board 1 and bonded thereto under heating and pressure using a convex roller 12 for heat and pressure bonding having the shape synchronous to the grooves 2 of the base board 1. At the time of bonding under heating and pressure, the almost center of the decorative sheet having the folds applied thereto is bonded under heating and pressure at first and a heat and pressure bonding part is successively moved toward both edges. In a separate mode, the edge of the decorative sheet is bonded under heating and pressure at first and the heat and pressure bonding part is successively moved toward the other edge.