The present invention relates to a pharmaceutical composition for topical administration and a preparation method therefor. In particular, the present invention relates to a pharmaceutical composition comprising (3aR, 5s, 6aS)-N-(3-methoxy-1, 2, 4-thiadiazol-5-yl)-5-(methyl(7H-pyrrolo[2, 3-d]pyrimidin-4-yl)amino)hexahydrocyclopenta[c]pyrrole-2(1H)-carboxamide, or a pharmaceutically acceptable salt thereof, and diethylene glycol monoethyl ether.