Disclosed is a slip-resistant rubber composition, which includes a substrate made of rubber, about 0.5 to about 3 parts by weight of a vulcanizer, about 2 to about 5 parts by weight of glass fibers, and about 1 to about 100 parts by weight of an additive, based on 100 parts by weight of the substrate, and has remarkably improved non-slip properties. Also, an outsole using the slip-resistant rubber composition and a method of manufacturing the outsole are provided, in which the outsole which results from subjecting the slip-resistant rubber composition to cutting, arrangement and vulcanization molding and in which one-side ends of the glass fibers are located at the lower surface of the outsole may exhibit remarkably improved non-slip properties so that a user who is wearing shoes having such an outsole is able to walk even on inclined ice.