The present invention relates to pharmaceuticals, foods and drinks, food additives, animal feeds and feed additives comprising an N-acylated hydroxyproline derivative or a salt thereof, and an amino sugar or a salt thereof and/or a glycosaminoglycan or a salt thereof as active ingredients, use of an Nacylated hydroxyproline derivative or a salt thereof for the production of an arthritis preventing or treating agent, and a method for preventing or treating arthritis which comprises administering an N-acylated hydroxyproline derivative or a salt thereof, and an amino sugar or a salt thereof and/or a glycosaminoglycan or a salt thereof.