PURPOSE: To provide an oral solution stably containing icariin for long period by compounding a nonionic surfactant.

CONSTITUTION: A nonionic surfactant, preferably 0.05-5.0wt.% of a polyoxyalkylene group-having ester or ether type surfactant such as polyoxyethylene glycol fatty acid ester or polyoxyethylene hardened castor oil is added to an oral solution containing icariin which is an active ingredient of Epimedium grandiflorum Morr var. thunbergianum and which has been reported to have functions such as antibody production-accelerating activity and sthenia tonic activity. The icariin may be prepared in the form of a tincture, solution extract, soft extract or dried extract obtained by the extraction of the Epimedium grandiflorum Morr war. thunbergianum. The oral solution is prepared in the form of a solution, emulsion or suspension, and the pH of the oral solution is preferably 2.5 to < 4 especially 2.5 to 3.5.