To provide a flow rate restraining top, hardly blocked up, even if foreign matter such as rust flows and comes, by restraining a maximum water quantity so that a water quantity of a certain degree or more does not flow out, even if a faucet is unconsciously fully opened.

This flow rate restraining top 1 is constituted so that a projecting part 11 is formed on the inflow side of a top; an inflow side opening 12 of a through-hole 14 is arranged in a top part of the projecting part or the vicinity; clearance is formed between an outside surface of a base part of the projecting part arranged on the inflow side of the top and an inner surface of an installing pipe member; a cylindrical projecting part is formed on the inflow side of the top; this projecting part is formed in a semispherical shape in the top part; and the inflow side opening of the through-hole is arranged in this semispherical part. Thus, even if the foreign matter such as rust flows and comes, the foreign matter does not stop in the projecting part, and stays in the clearance of the base part, so that blocking-up of the inflow side opening of the through-hole by the foreign matter, can be prevented.