A fitting pressing member 44 includes: a first opening 44b1 that opens inside a fitting 11 of an endoscope 2 a second opening 44b2 that is communicably connected to the first opening 44b1 and is connectable to a fluid supply source a cylindrical portion 44g formed from the first opening 44b1 to a predetermined position PL, the cylindrical portion 44g covering a part of a hollow portion 44b3 communicably connected to the first opening 44b1 and the second opening 44b2 a narrowing portion 44e including a side face whose outer diameter increases from the predetermined position PL toward the second opening 44b2, the narrowing portion 44e covering the other part of the hollow portion 44b3 and a plurality of grooves 44f formed over a predetermined area from the predetermined position PL in an outer surface of the narrowing portion 44e.
