According to the present invention, an anti-allergic agent is provided which includes a polysaccharide comprising galactose, glucose and rhamnose as constituents, or includes a microorganism belonging to a genus Bifidobacterium and extracellularly producing the polysaccharide. The anti-allergic agent of the present invention can be used in oral compositions and compositions for external application, and is suitable for use in products such as food products, pharmaceutical products, and cosmetics.