Anti-fatigue agents containing dioxabicyclo[3.3.0]octane derivatives such assesamin which is an ingredient contained in sesame, as well as pharmaceuticalcompositionsand physiologically functional foods that contain such anti-fatigue agents aredisclosed.These compounds can safely be administered to humans and animals alike andhence allowfor continued ingestion while proving effective in promoting an improvement ofstamina, anincrease of body strength, a relief of fatigue, and recovery from fatigue.