A chamber for reducing operating noise of a purge control solenoid valve (PCSV) for an evaporative emission control system comprises a first housing into which operating noise of the PCSV enters. The first housing has an inner space to change a cross sectional area of an operating noise path or an operating noise transfer direction at least once. A second housing has an upper portion coupled to a lower portion of the first housing to transfer the operating noise outside. At least one end of the chamber in a length direction thereof is connected with a vapor hose which connects a canister collecting fuel evaporation gas generated from a fuel tank with the PCSV to deliver the fuel evaporation gas to an engine and through which the fuel evaporation gas flows.