Cartridge system, cartridge, and method for loading jig unit

In order to be able to load a jig unit into an introduction device without closing the opening after the jig unit is accommodated from the opening of a cartridge, this cartridge system is configured to comprise: a jig unit (1) having a plurality of arms (211, 212) that can be opened and closed, and a connection member (4) that can be connected to a power transmission unit (230) that passes through the inside of a sheath (220); and a housing (6) having a housing region (6S) in which the jig unit is housed, a tip opening (60b) provided on the tip side of the housing region, and a base opening (3b) provided on the base side of the housing region and into which the sheath can be inserted, the housing having a locking part (64). The clamping part (64) allows the clamp unit which is inserted from the front end opening and moves towards the base end side to pass through, and restricts the passing of the clamp unit which moves towards the front end opening and towards the front end side. 为了在从盒的开口容纳了夹具单元之后不堵塞所述开口就能够向导