An object of the present invention is to make it possible that a pyridine antibacterial/antifungal agent is dispersed stably in a liquid for appropriate impartation of the pyridine antibacterial/antifungal agent to fibers, and that when fibers are processed with the agent which is mixed with various other treating agents such as dyes and softeners, there is no negative influences on the process of the fibers for imparting antibacterial/antifungal properties. An antibacterial/antifungal properties-imparting agent contains a pyridine antibacterial/antifungal agent a modified polysaccharide having reduced hydroxyl groups and a wetting agent but does not contain a surfactant. After applying the antibacterial/antifungal properties-imparting agent to fibers, the fibers undergo a heating process.