PURPOSE: To obtain a plywood having no need for a resin treatment by a method wherein the outside part of a bamboo is developed flat and bonded to a core plate.

CONSTITUTION: A boring blade fixed by a bearing 4 is rotated, and only a bamboo 6 fixed at four sides is fed in a direction 8 by roller guides 5. The bamboo 6 is cracked by a part 9 of the bearing. The bamboo 6 is bored, and only an outside part 1 remains. This is developed flat. The outside part 1 is straightened by a thermal treatment, dried, and bonded to a core plate.