To provide an air nozzle to positively seal the upper end opening of an extraction cartridge.

The air nozzles 41A and 41B are installed in series to a head body 50 of a pressure head. The air nozzle 41A comprises the nozzle body 80A, the nozzle head 81A, a compression spring 82A, a stopper 83A and the like. An O-ring 86A is fitted to the nozzle head 81A. The diameter ψA of the lower end part 87A of the nozzle head 81A is is similar in size to the diameter ψa of the extraction cartridge 2. The air nozzle 41A is positioned correctly by fitting the lower end part 87A to the inner circumferential face of the extraction cartridge 2. The air nozzle 41 B is similar in structure and size to those of the air nozzle 41A, however, it is projected downward. After pressurization, the air nozzle 41A is separated from the extraction cartridge 2 at first, and then the air nozzle 41B is separated from the extraction cartridge 2. Therefore, the air nozzles 41A and 41B are easily separated.