An agent for applying to mucosa capable of persistently exerting a therapeutic effect on disorders such as inflammation and lesions in the mucosa even by a lower frequency of administration because the agent can stay at a diseased site for a long period of time by exhibiting a high staying property in a mucosal epithelial layer is provided, said agent for application to mucosa containing glycosaminoglycan (GAG) into which a hydrophobic group is introduced via a binding chain, as an active ingredient.