Abstract: A method of and apparatus for feeding and discharging air for pneumatic jigs, includes feeding and discharging pressure air to and from air chambers, which are opened at their respective lower ends, and which are formed in water-filled tanks, to vertically vibrate water in the water tanks, and separate a pulverulent body on the water. The air feeding and discharging steps are carried out repeatedly, and with having overlapping periods. The apparatus comprises an outer cylindrical casing, and an inner casing provided rotatably in the outer casing, the outer casing being provided in a circumferential wall thereof with a communication port communicated with air pipes opened into the air chambers. A plurality of air ports communicate with an air feeding unit which is capable of feeding air of a plurality of different pressures to the air chambers, and a discharge port is provided.