In this case, after blood vessels and other tissues lying around the bronchus H4 and the bronchus H4 have been separated from each other to expose the external surface of the bronchus H4, the bronchus H4 can be ligatured from the outside by using a clip 121 or a comparatively thick thread-like material, as shown in FIG. 19. [0126]FIG. 19 shows the state of embolization of the bronchus H4.