According to the present invention, there is provided a clip cartridge in which a clip having a structure enabling a user to easily perform a series of procedures can be easily and reliably mounted on a treatment instrument body. A clip cartridge (200) according to the present invention includes an inner case (30) that has a first accommodation region (32) for accommodating a clip (110), and an outer case (40) that has an elongated insertion hole (43) into which a treatment instrument body (90) is inserted, and a second accommodation region (42) which accommodates the inner case (30) so as to be movable. The treatment instrument body (90) is inserted into the insertion hole (43), and an operation wire is pressed forward so that a distal connection portion and a diameter enlargement portion of the sleeve protrude from the sheath to a distal side and enter the second accommodation region (42), and so that a diameter enlargement portion is elastically enlarged in diameter. The operation wire is further pressed so as to bring a distal connection portion and the clip (110) into a mutually connected state. The operation wire is pulled so that the inner case (30) moves backward relative to the outer case (40) so as to press the sleeve backward, thereby drawing the diameter enlargement portion into the sheath while reducing the diameter enlargement portion in diameter.
