A chemical circulation system is provided to control the amount of chemicals to be circulated by controlling air pressure supplied to a chemical circulation pump. A chemical bath(130) is used for storing chemicals. A heating unit(124) is used for maintaining constantly the temperature of the chemicals supplied to the chemical bath. A chemical filter(126) is used for filtering impurities of the chemicals. A chemical circulation pump(128) is used for controlling the amount of chemicals according to a position of a wafer transferred to the chemical bath. An air supply unit(150) controls the air pressure applied to the chemical circulation pump in order to control the amount of chemicals to be circulated.
