PURPOSE: To prepare the subject structured material having an angle portion accurately and readily molded, by gradually reducing the arrangement density of warps at the approximately longitudinally center portion of a three-dimensionally woven plate-like fabric toward the inner surface thereof from the outer surface, bending the inner surface of the center portion in a L-shaped cross section and subsequently fixing the shape with a matrix.

CONSTITUTION: In three dimensionally woven fabric formed by arranging warps 1 in multistage and in parallel, arranging wefts 2 in multistage and in parallel in a state orthogonal to the warps 1, arranging vertical fibers 3 between the rows of the warps 1 from the front surface of the multistaged weft groups to the back surface in a snaking state, arranging the neighbor vertical fibers 3' between the neighbor row of the warps and the further apart row of the warps in a snaking state wherein the multistage crossed product of the warps 1 and wefts 2 is integrated and tied with the groups of the vertical fibers 3 to form the plate-like woven fabric, the density of the warps 1 at the longitudinally approximately central portion of the plate-like woven fabric a having desired thickness, width and length is gradually reduced from one outer surface toward the other inner surface and the plate-like woven fabric is bent in a L-shaped cross section using the inner surface as a bending inner surface, followed by fixing the shape with a matrix b in the state to provide the objective angle structured material.