PROBLEM TO BE SOLVED: To provide a coupling implement which does not easily cancel coupling in spite of repeated operation to cancel the coupling and the use in a circumstance to get wet with water and cancels the coupling when necessary.SOLUTION: A coupling implement 1 includes a first member 2 and a second member 3 which can be engaged with and disengaged from each other. The first member 2 is provided with a plurality of first protrusions 22 at intervals along a circumferential direction on a facing surface 26 where the first member butts against the second member 3. The second member 3 is provided with a plurality of second protrusions 32 which are inserted between the adjacent first protrusions 22 to form a circumferential wall with the first protrusions 22 on a facing surface 36 where the second member 3 butts against the first member 2. The first protrusion 22 and the second protrusion 32 have at least one engaging protruding part 24, 34 that engage in a fall-off preventing state where the fall-off in a direction in which the first protrusion 22 is separated from the second protrusion 32 is prevented on mutually facing side surfaces.
