Gasper and grasping tool

A grasper comprising:

• an introduction tube that is capable of being inserted into a body cavity;
• an operational elongate body that is inserted into the introduction tube so as to advance and retract;
• a grasping tool that is attached to a distal end portion of the introduction tube and is operated by a relative movement between the operational elongate body and the introduction tube so as to grasp a body tissue,
• wherein the grasping tool further comprises:
• a plurality of grasping arms which are indwellable inside of a patient's body;
• a retracting portion in which a proximal end is connected to the operational elongate body, and the retracting portion retracts a portion of the body tissue between the plurality of grasping arms;
• and
• a pressing ring which is fitted into an outer circumference of the plurality of grasping arms, and as the plurality of grasping arms are moved toward a proximal end side, the pressing ring moves toward a distal end side with respect to the moved plurality of grasping arms, and
• wherein when the retracting portion is operated to be moved more than a predetermined distance in a proximal direction by operating the operational elongate body, the plurality of grasping arms are closed so as to grasp the body tissue:
• the retracting portion has a locking portion at a distal end of the retracting portion, the locking portion is lockable to a portion of the body tissue so as to retract a portion of the body tissue between the plurality of grasping arms,
• the locking portion is disposed so as to be relatively moved with respect to the plurality of grasping arms along a central axial line of the grasping arms and is operated to be moved with respect to the grasping arms by the operational elongate body,
• when the locking portion is operated to be moved more than a predetermined distance toward the proximal end by the operational elongate body, the plurality of grasping arms are closed with a movement of the locking portion so as to grasp the body tissue such that the locking portion is locked to the grasping arms when the locking portion is moved by the predetermined distance, and such that when the locking portion is moved more than the predetermined distance, the grasping arms are moved toward the proximal end integrally with the locking portion, and the grasping arms being predisposed to spread out are inwardly pressed by the pressing ring so as to be closed.