Medical devices of the present invention is a medical device for the treatment endoscopically the bag-like cavity opening in the body has a plurality of communication passages which open to the outside surface, said bag-like cavity a suction member that is inserted, it abuts against the opening of the bag-like cavity, and a medical device, characterized by comprising a, a closure member for sealing said opening hermetically.本発明の医療機器は、体内に開口する袋状の腔を内視鏡的に治療するための医療機器であって、外面に開口する複数の連通路を有し、前記袋状の腔内に挿入される吸引部材と、前記袋状の腔の開口に当接されて、前記開口を気密に密閉する閉鎖部材と、を備えることを特徴とする医療機器である。