A procedure for forming an opening in a tubular organ surface while observing images from an endoscope introduced into a tubular organ through a natural opening, and performing observation and treatment of an organ in an abdominal cavity through the opening, including the steps of: inserting an endoscope into a target tubular organ through a natural opening of a subject checking and identifying a region without other organs or blood vessels inserting a perforating treatment instrument perforating with the perforating treatment instrument inserting the endoscope into the abdominal cavity through the perforated portion inserting a surgical treatment instrument through the perforated portion performing surgery inserting a suturing instrument and suturing the perforated portion, wherein the endoscope is replaced by an ultrasonic endoscope in at least one of the steps.
