A clip treatment tool comprising: a clip body that has two arm portions (20A, 20B) that face each other and that are configured to open and close, the clip body further having a folded portion that connects proximal end parts of the two arm portions (20A, 20B); a tightening ring that is attached to the two arm portions (20A, 20B) and functions to close the two arm portions (20A, 20B) in accordance with a movement of the clip body proximally in an axial direction relative to the tightening ring; a pressing tube that has at least one opening (50;52) formed in an outer surface thereof and extending in the axial direction, the pressing tube further having a distal end part to which the tightening ring is removably attached, the pressing tube being configured to allow the clip body to be contained therein in accordance with the proximal movement of the clip body; and a coupling member that has a distal end part to which the folded portion is removably connected and a proximal end part to which a distal end part of an operation wire is fixed, the coupling member coupling the clip body and the operation wire to each other, wherein the coupling member is contained in the pressing tube, wherein each of the two arm portions (20A, 20B) has, at both proximal end parts thereof in a width direction, a recessed portion (26A, 26B) having a length in an extension direction larger than a size of the tightening ring in the axial direction, wherein, when the clip body moves proximally relative to the tightening ring such that proximal end parts (24A, 24B) of the recessed portions (26A, 26B) move to positions beyond a proximal end part of the tightening ring, the two arm portions (20A, 20B) move in directions away from each other due to an elastic force, the tightening ring is latched to the recessed portions (26A, 26B), and the clip body is locked to the tightening ring, characterized in that in a state in which the the clip body is locked to the tightening ring, and in which the tightening ring and the pressing tube are separated from each other, when the tightening ring is squeezed from both sides of the outer peripheral surface thereof in directions in which the two arm portions (20A, 20B) face each other, the proximal end parts (24A, 24B) of the recessed portions (26A, 26B) move to positions where the proximal end parts of the recessed portions (24A, 24B) contact an inner peripheral surface of the tightening ring, and the clip body and the tightening ring are unlocked, and wherein, in a state in which the clip body and the tightening ring are unlocked, in accordance with a proximal movement of the tightening ring relative to the clip body, the two arm portions (20A, 20B) are configured to open from a closed state and enter an open state. a clip body that has two arm portions (20A, 20B) that face each other and that are configured to open and close, the clip body further having a folded portion that connects proximal end parts of the two arm portions (20A, 20B); a tightening ring that is attached to the two arm portions (20A, 20B) and functions to close the two arm portions (20A, 20B) in accordance with a movement of the clip body proximally in an axial direction relative to the tightening ring; a pressing tube that has at least one opening (50;52) formed in an outer surface thereof and extending in the axial direction, the pressing tube further having a distal end part to which the tightening ring is removably attached, the pressing tube being configured to allow the clip body to be contained therein in accordance with the proximal movement of the clip body; and a coupling member that has a distal end part to which the folded portion is removably connected and a proximal end part to which a distal end part of an operation wire is fixed, the coupling member coupling the clip body and the operation wire to each other, wherein the coupling member is contained in the pressing tube, wherein each of the two arm portions (20A, 20B) has, at both proximal end parts thereof in a width direction, a recessed portion (26A, 26B) having a length in an extension direction larger than a size of the tightening ring in the axial direction, wherein, when the clip body moves proximally relative to the tightening ring such that proximal end parts (24A, 24B) of the recessed portions (26A, 26B) move to positions beyond a proximal end part of the tightening ring, the two arm portions (20A, 20B) move in directions away from each other due to an elastic force, the tightening ring is latched to the recessed portions (26A, 26B), and the clip body is locked to the tightening ring, characterized in that in a state in which the the clip body is locked to the tightening ring, and in which the tightening ring and the pressing tube are separated from each other, when the tightening ring is squeezed from both sides of the outer peripheral surface thereof in directions in which the two arm portions (20A, 20B) face each other, the proximal end parts (24A, 24B) of the recessed portions (26A, 26B) move to positions where the proximal end parts of the recessed portions (24A, 24B) contact an inner peripheral surface of the tightening ring, and the clip body and the tightening ring are unlocked, and wherein, in a state in which the clip body and the tightening ring are unlocked, in accordance with a proximal movement of the tightening ring relative to the clip body, the two arm portions (20A, 20B) are configured to open from a closed state and enter an open state.