PROBLEM TO BE SOLVED: To provide an oral liquid formulation containing vitamin C and peoniflorin and being stable for the long term. SOLUTION: This oral liquid formulation comprises vitamin C and peoniflorin and has about 5.0 to about 6.0 pH. The oral liquid formulation preferably further comprises a nonionic surfactant in an amount of about 8-200 wt.% based on vitamin C. The nonionic surfactant is preferably one or more kinds of nonionic surfactants selected from a polyoxyethylene hardened castor oil, a polyoxyethylene sorbitan fatty acid ester, a saccharide fatty acid ester, a polyoxyethylene polyoxypropylene glycol and a polyethylene glycol fatty acid ester.
