A closing member (16) is disengageably fitted to one end of a cylindrical-shaped guide member (4) to close an opening (4a) of the guide member (4). A water-absorbing agent (3) made of water-absorbing resin powder is accommodated in the guide member (4) toward the one end. A column-shaped plug member (2) made of water-swellable fibers is accommodated in the guide member (4) at a location closer to the other end than the water-absorbing agent (3). A push rod (5) is inserted into the guide member (4) through an opening (4b) thereof located at the other end. With the opening (4a) at the one end of the guide member (4) inserted in an anus, the push rod (5) is operated to push the water-absorbing agent (3) and the plug member (2) through the opening (4a) at the one end of the guide member (4) into a rectum. The plug member (2) absorbs water in internal contents and expands to plug the rectum, while the water-absorbing agent (3) also absorbs water in the internal contents. Thus, the internal contents can be prevented from leaking out through the anus.