To quickly sale coffee of regularly stabled good quality by preliminarily storing a prescribed quantity of the coffee extracted from a raw material in a storing vessel, detecting the pH of the coffee in the storing vessel, and disposing the coffee in the storing vessel when the change quantity of pH is out of a standard value.

When it is set that 26 cups of coffee, for example, are collectively extracted, the changer 22 of an extracting equipment 6 is first lowered to put a paper filter between a funnel 21 and it, coffee powder for 26 cups is discharged from a raw material carrying-out device 3 into the changer 22. A hot water feeding solenoid valve 16 is opened to spray hot water for 26 cups from a hot water tank 2 over the coffee powder in the chamber 22. Thus, 26 cups of coffee are extracted, and the resulting coffee solution is stored in a tank 27. The pH of the coffee solution is detected by a pH sensor 32, and when the oxidation of coffee is advanced, and a deterioration is judged, a discharge solenoid valve 31 is opened to dispose the coffee solution in the tank 27 to a disposing vessel 45.