PROBLEM TO BE SOLVED: To provide an endoscopic treatment instrument improved in operability, reduced in cost and constituted so as to perform continuous biopsy.SOLUTION: In the endoscopic treatment instrument in which a long insertion portion 275 inserted into the channel 215 of an endoscope 202 from an operation unit operated by an operator and a distal end treatment unit 277 for collecting biotissue is provided at the distal end part of the insertion portion 275, a distal end control unit 278 for controlling the position of the distal end treatment unit 277 is provided in the direction pulling out the distal end treatment unit 277 after the insertion portion 275 is inserted into the channel 215. The insertion portion 275 has an inside sheath 76 and the outside sheath 280 which covers the outer periphery of the inside sheath 76 in a freely slidable manner and the outside sheath 280 is constituted so as not only to be positioned with respect to the endoscope 202 but also to be locked with the distal end treatment unit 277 in a direction pulling back the distal end treatment unit 277.
