There is provided a lightweight sandwich panel of exceptional utility, which satisfies the flexural strength and in-plane shear strength requirements for an inner wall material used in aircraft. The sandwich panel comprises a laminating material in which a plurality of fiber bodies_is laminated, and a surface material, the laminating material and the surface material being laminated in the stated order from the inside to the outside on the upper and lower surfaces of a hollow columnar core. The laminating material comprises at least four unidirectional fiber bodies each of which has fibers aligned in a uniform direction and is laminated so that each of the fiber directions thereof is at approximately 0 , +45°, −45°, and 90°, respectively, in relation to one edge of the sandwich panel. The unidirectional fiber bodies are stitched together using a stitching yarn.