To provide a click mechanism that can be easily retrofitted in a single lever combination faucet.

A first annular member can be fixed in external fit on an end of a small-diameter cylindrical portion of a casing of a valve unit. A second annular member can be relatively rotatably engaged with the first annular member. First springy bodies are retained on the second annular member and pressed on corrugations formed at an end face of the first annular member. The second annular member has arc surfaces at an end face away from the first annular member, and has corrugations lining on the arc surfaces along arc extension. A third annular member can be moved relative to the second annular member along the arc surfaces. Second springy bodies are retained on the third annular member and pressed on the corrugations on the second annular member. An operating lever is fixed on a valve system driving rod of the valve unit, as passed through the third annular member against relative pivoting and against relative rotation, and passed through the second annular member for relative pivoting along the extension of the arc surfaces and against relative rotation.