The present invention provides a stable gel composition for mycosis treatment, with increased absorption and permeation of (2R,3R)-2-(2,4-difluorophenyl)-3-(4-methylenepiperidin -1-yl)-1-(1H-1,2,4-triazol-1-yl)-butan-2-ol into a target site (skin and nail). The gel composition for mycosis treatment, comprises (2R,3R)-2-(2,4-difluorophenyl)-3-(4-methylenepiperidin-1-yl) -1-(1H-1,2,4-triazol-1-yl)-butan-2-ol or an acid addition salt thereof, a lower alcohol, a polyhydric alcohol and a gel-forming polymer. The gel composition of the present invention increases permeation of the above compound into a target site and into the nail. The gel composition of the present invention allows the drug to be directly and rapidly absorbed and permeated into a target site in a constant manner, for mycosis treatment, particularly onychomycosis treatment.
