To realize a board of bamboo combination, which keeps a strength and, at the same time, in which neither warpage nor twisting occurs, by a method wherein a broad bamboo plate, which is obtained by developing a circular bamboo, and narrow bamboo plates, each of which is obtained by dividing the circular bamboo, are assembled together.

In this combined board, a broad plate, which is obtained by developing a circular bamboo, is used as a front surface material 2. A rear surface material 5 is obtained by repeadedly laminating and pressure-bonding narrow plates 4 obtained by dividing the circular bamboo through an adhesive in the direction of the thickness to one another by facing its front surfaces or its rear surfaces to each other or its front surface to its rear surface. A combined board 7 is produced by laminating and pressure-bonding the front surface material 2 and the rear surface material 5 through the adhesive in such a manner that the direction of the thickness of the front surface material 2 is set normal to the direction of the thickness of the narrow plates 4. As a result, the combined board consisting of the front surface material and the rear surface material is prevented from being warped and twisted and it can fully utilize the pattern and strength characterizing the bamboo.