PROBLEM TO BE SOLVED: To improve operability.SOLUTION: A case body 12 comprises a first main wall part 21 and a second main wall part 22 which are opposed to each other, and a peripheral wall part 23 connecting both main wall parts. The peripheral wall part 23 is formed with an insertion port 24 in which a cartridge body 11 is inserted. In an inner face of the first main wall part 21, a pair of support protrusions 26 arranged at intervals in an orthogonal direction orthogonal to both an opposite direction Z opposing to both main wall parts and an insertion direction X in which the cartridge body 11 is inserted from the insertion port 24, and guide protrusions 27 arranged between the pair of support protrusions 26 in the orthogonal direction are provided. An amount of projection of the guide protrusions 27 is gradually increased from a rear side to a front side in the insertion direction X. The cartridge body 11 is supported, from the first main wall part 21 side, by the front end side of the guide protrusions 27 and the support protrusions 26, and is held by the front end side of the guide protrusions 27, the support protrusions 26 and the second main wall part 22. A fitting part 34 detachably fitted to a fitted part 34 is provided in the cartridge body 11.
