A functional area is provided in a partial toe area on a sole side of a sock. Provided are a lower knitting needle area which is knitted by a lower knitting needle, and an upper knitting needle area which is knitted by an upper knitting needle; the lower knitting needle area and the upper knitting needle area are arranged in alignment with a direction of use on the toe area of an inner side of thesock S; and a first functional area is further provided, wherein the lower knitting needle area and the upper knitting needle area are knitted by a functional yarn which is different from the yarn for knitting other areas of the toe area of the inner side. The first functional area may be provided in a specific area of the toe area of the inner side. If the first functional area is knitted with the functional yarn with a high frictional resistance, a clamping force of the specific area is increased.