Abstract: Cineole C10H18O is used for as treatment agent for surface-treating wooden building materials. Eucalyptus oil mainly containing cineole may be utilized for the solution as a substitute. Japan wax, beeswax, carnauba wax or nonionic surface active agent is available as the additives of the agent. Since cineole has various pharmaceutical effects, wooden building materials impregnated therewith may exhibit preservability and protecting effects from molding and infesting with insects without spoiling natural appearance of wood, besides may contribute to present floorboards being sanitary and hygienic especially in humid climates.