The present invention aims to provide a gel composition for mycosis treatment, which ensures good 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 present invention also aims to provide a gel composition for mycosis treatment, which is excellent in stability of this drug. It is a gel composition for mycosis treatment, which 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 is excellent in permeation of KP-103 into a target site and also excellent in permeation into the nail. Thus, 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, and thereby produces an excellent effect in mycosis treatment, particularly onychomycosis treatment.
