The present medical instrument includes a snare wire that is inserted into a channel in an insertion portion of an endoscope so as to be capable of advancing and retracting and a first portion and a second portion, and the first portion is fitted to the channel of the insertion portion And a substantially tubular cap member which can be attached to a distal end and has an internal space, wherein a snare wire forms a loop on the inner surface on the distal side of the second member side of the cap member along the inner surface And a guide member for restricting backward movement of the snare wire toward the insertion portion is provided.本医療器具は、内視鏡の挿入部内のチャンネルに進退可能に挿通されるスネアワイヤと、第１部および第２部を有し、前記第１部を前記チャンネルの位相に合わせて前記挿入部の先端に装着可能であり、内部空間を有する略筒状のキャップ部材とを備え、前記キャップ部材の前記第２部側の先端側の内面には、前記内面に沿って前記スネアワイヤがループを形成するように案内し、かつ、前記スネアワイヤの前記挿入部側への後退を規制するガイド部材が設けられている。
