PURPOSE: To provide a molding method and mold of a faucet having a rubber ring holding groove wherein it is unnecessary to use a complicated core mold and therefore a large quantity of man hours are unnecessary for maintenance.

CONSTITUTION: At the time of molding of a faucet 1 having a rubber ring holding groove 11 by making use of an injection mold constituted of a core mold 2 and outer molds 3, 4, the rubber ring holding groove molding part 21 of the core mold 2 is heated and as for the other part of the core mold 2, the cooled one is used. Then after molding of the faucet 1 by casting thermoplastic resin into a cavity to be formed among the core mold 2 and outer molds 3, 4, the outer mold 3 is released, though the thermoplastic resin molded by a cooled part 22 of the core mold 2 is cooled and solidified, the core mold 2 is separated from the faucet 1 while a part molded by the rubber ring holding groove forming part 21 of the core mold 2 is still under a softened state.