An endoscopic treatment instrument includes a sheath； a basket section formed by elastic wires； a manipulation wire connected to the basket section； and a distal end cover attached to a distal end of the sheath. The distal end cover has: a first opening； a second opening； an inner peripheral surface disposed between the first and second opening； and a curved surface bent over the whole circumference in t circumference direction of the distal end cover. Each of the plurality of the elastic wires has: a proximal end portion, a distal end portion, and a maximum diameter section. A radius of curvature of the curved surface is smaller than a radius of curvature of each of the plurality of the elastic wires. A contact position of the elastic wires and the curved surface moves in accordance with a retraction of the elastic wires.
