Insole and method of producing the same

An insole having a shank comprising a sheet of a synthetic resin reinforced with fibers wherein said fibers have a specific modulus of elasticity of at least about 6.times.10.sup.9 mm and a specific strength of at least about 5.times.10.sup.7 mm and comprise carbon fibers or a combination of carbon fibers with glass fibers or aromatic polyamide fibers, wherein said combination comprises at least 10% by volume of carbon fibers, and wherein the volume ratio of said fibers in said synthetic resin is about 30 to about 85% by volume, said shank being put on the insole.