An external medicine for treating dermatitis wherein an adrenocortical steroid is included by a cyclodextrin; and 0.025 to 0.5% by weight of the adrenocortical steroid, 0.2 to 30% by weight of the cyclodextrin, and 0.5 to 55% by weight of dextran or pullulan are dissolved in an aqueous solution containing polysaccharide; and 0.5 to 55% by weight of xyloglucan, trehalose, laminaran, krestin, and pectin are blended. Grape sugar, mutan, lentinan, sodium chloride, and potassium chloride are comprised in the medicine. The medicine has a higher cure effect on atopic dermatitis and psoriasis vulgaris.