PURPOSE: To save the fuel cost of a tea-preparing apparatus and improve the quality of the prepared tea by disposing an oxygen-separating device, supplying the resultant oxygen-reduced air to a tea leaf-receiving chamber to control the oxidative change of the tea leaves and simultaneously employing the oxygen- enriched air as a combustion air for a combustion equipment.

CONSTITUTION: A gas-separating device 12 provided with a gas-separating membrane 11 for separating oxygen is disposed in a tea-preparing apparatus 12. Air in a tea-receiving chamber of the tea-preparing apparatus or in the atmosphere is supplied to the gas-separating membrane 11 through a gas- supplying piping 13. An oxygen-reduced air obtained from an impermeable gas-taking piping 14 disposed on the gas-supplying side of the gas-separating membrane 11 is subsequently supplied to a tea leaf-receiving chamber or a heat exchange air inlet of a heat exchanger communicated with the tea-receiving chamber to control the oxidative change of the tea leaves. An oxygen-enriched air obtained from a permeable gas-taking piping 15 disposed on the gas- permeating side of the gas-separating membrane 11 is also supplied to a combustion opening of a combustion equipment attached to the tea-preparing apparatus to utilize the air as a combustion air.