Abstract: A fiber grid reinforcement is of a flat shape and has first and second directions perpendicular to each other. The fiber grid reinforcement includes a plurality of first fiber bundles, a plurality of second fiber bundles, and a resin material. The first fiber bundles are generally disposed along the first direction and generally parallel to one another. Each of the first fiber bundles includes at least one first group of fibers. The second fiber bundles are generally disposed along the second direction and generally parallel to one another. Each of the second fiber bundles inbcludes at least one second group of fibers. The second fiber bundles intersect perpendicular to the first fiber bundles at intersecting sections so as to form a grid structure. The first group and the second group of fibers are layered alternately at the intersecting sections in such a manner that at least one outermost layer is the second group. The resin material bonds fibers in each group, and bonds the groups to one another.