An endoscope treatment tool comprising: a flexible sheath; a wire that is inserted into the sheath; a treatment unit that is provided at a distal end of the wire; a connector body having a tubular shape to which a proximal end of the sheath is connected; a water injection connector that is provided at the connector body; and an operation part body that is connected to a proximal end of the connector body and moves the wire forward and backward in an axial direction of the sheath such that the treatment unit projects and retracts from a distal end of the sheath, wherein the connector body is connected to the operation part body such that the connector body is rotatable around a rotation axis, characterised in that: the operation part body includes a rotation stopper, the connector body includes an abutting surface, and the connector body is capable of transitioning between a rotation restricted state, in which the abutting surface abuts the rotation stopper such that the connector body is restricted to be rotatable only in one direction, and a rotation allowed state, in which the abutting surface abutting the rotation stopper is released and rotation of the connector body in both directions is allowed, by rotating with respect to the operation part body. a flexible sheath; a wire that is inserted into the sheath; a treatment unit that is provided at a distal end of the wire; a connector body having a tubular shape to which a proximal end of the sheath is connected; a water injection connector that is provided at the connector body; and an operation part body that is connected to a proximal end of the connector body and moves the wire forward and backward in an axial direction of the sheath such that the treatment unit projects and retracts from a distal end of the sheath, a wire that is inserted into the sheath; a treatment unit that is provided at a distal end of the wire; a connector body having a tubular shape to which a proximal end of the sheath is connected; a water injection connector that is provided at the connector body; and an operation part body that is connected to a proximal end of the connector body and moves the wire forward and backward in an axial direction of the sheath such that the treatment unit projects and retracts from a distal end of the sheath, wherein the connector body is connected to the operation part body such that the connector body is rotatable around a rotation axis, characterised in that: the operation part body includes a rotation stopper, the connector body includes an abutting surface, and the connector body is capable of transitioning between a rotation restricted state, in which the abutting surface abuts the rotation stopper such that the connector body is restricted to be rotatable only in one direction, and a rotation allowed state, in which the abutting surface abutting the rotation stopper is released and rotation of the connector body in both directions is allowed, by rotating with respect to the operation part body. the operation part body includes a rotation stopper, the connector body includes an abutting surface, and the connector body is capable of transitioning between a rotation restricted state, in which the abutting surface abuts the rotation stopper such that the connector body is restricted to be rotatable only in one direction, and a rotation allowed state, in which the abutting surface abutting the rotation stopper is released and rotation of the connector body in both directions is allowed, by rotating with respect to the operation part body.