To obtain a foliar spray agent, capable of enhancing the yield and quality of rice and useful for grain filling cultivation of the rice by formulating a vinegar comprising branched oligosaccharide-containing saccharides as ingredients with a specific sweetener.

This foliar spray agent is obtained by formulating a vinegar comprising branched oligosaccharide-containing saccharides as ingredients with stevias useful as a sweetener. The foliar spray agent is preferably used and sprayed on the latter half of a grain filling period of rice. A vinegar prepared by carrying out the acetic acid fermentation of a mixture of the branched oligosaccharide-containing saccharides with an alcohol for brewing or conducting the alcoholic fermentation and acetic acid fermentation of the branched oligosaccharide-containing saccharides is preferred as the vinegar. Stevias with >5/100 content of diterpene glycosides in solids are preferred as the stevias. The foliar spray agent is preferably formulated at a ratio of ≤50 pts.wt. solids of the stevias based on 100 pts.wt. solids of the branched oligosaccharide- containing saccharides.