To provide a water-saving tool for a faucet at a low cost being capable of being installed to an existing faucet, being capable of conducting installation works without stopping the supply of water and having a simple structure.

The water-saving tool for the faucet is mounted between the large diametral section 6 of an operating handle shaft 2 for the faucet 1 and a packing plate 10. The water-saving tool is constituted so that the quantity of a top 5 for the faucet opened is limited by limiting the movement of the handle shaft 2. Accordingly, a large quantity of water is not discharged carelessly.