To provide a carpenter sand file manufacturing method capable of demonstrating high performances such as low cost, excellent convenience and usability, and high filing sharpness.

Unit materials which are formed in a shape of improving the density and toughness by grinding bamboo unit materials 11, 12, 12, 13, 14 as groups of tubular fibers are constituted by adhesion of the face 11 to the face 11, and the face 13 to the face 13 with their characteristics facing each other to generate strong repulsion against the outward bending. High strength against the pressure of grinding the facing material can be demonstrated even when providing a tapered shape required for a carpenter sand file core.