AERATION AGITATOR

PROBLEM TO BE SOLVED: To provide an aeration agitator in which an axial-flow impeller disposed in a draft tube is rotated while supplying air in the draft tube, and which performs aeration agitation to a liquid to be processed, wherein the amount of the air bubble that has finished contact with the liquid that inflows from a suction port of the draft tube upper part is reduced, and the aeration agitation efficiency is improved.SOLUTION: The aeration agitator includes: a draft tube 40 provided in a liquid to be processed, the liquid being accommodated by a treatment tank TK; an axial-flow impeller 85 disposed in the draft tube 40 and rotating by the driving of a rotation driving part 82; an air supply part 50 supplying air in the draft tube 40 through an air discharge port 59a; a cover 61 forming a space in which the top surface and the peripheral surface are occluded in an outer periphery of the draft tube 40; and an air discharge channel 63 whose one end is coupled with the space, and at the other end of which an opening 61a locating in the water surface neighborhood of the liquid is formed.