Biomaterials should be biocompatible and biodegradable. Many researches had been studied to upgrade biomaterials to deliver various types of drugs. In this respect, natural polymers have been catching on as a biomaterial. To immobilize drugs using natural polymer, photo-immobilization method has been designed. This method has several advantages. For photo-immobilization, photo-reactive functional group should be introduced to natural polymer. According to purpose of application, you could choice one of the photo-reactive functional group. Finally, many types of chemically modified natural polymers, which are photo-reactive natural polymer derivatives, have been prepared and studied to apply in medical field.