A clip device 1 that has a coil-shaped tubular body 6 that is inserted through a curvable treatment instrument insertion channel of an endoscope, the tubular body 6 includes a proximal side coil (first coil) 10 that has a spring constant per unit length of 15 N/mm to 500 N/mm and is disposed on the proximal end side of the tubular body 6 and a distal end side coil 11 that is connected to the distal end of the proximal side coil 10, has a greater inner diameter than the inner diameter of the proximal side coil 10, has a spring constant per unit length of 15 N/mm to 500 N/mm, and has a spring constant that differs from the spring constant of the proximal side coil 10, with the ratio of the spring constants of the proximal side coil 10 and the distal end side coil 11 is greater than 1.0 and less than or equal to 2.0. In accordance with the present invention, it is possible to provide a treatment instrument for an endoscope, in which even in a case where a strong compressive force is applied to the coil-shaped tubular body in a curved channel of endoscope, it is possible to suppress a plastic deformation of the tubular body due to a slippage of the coil wire.
