PROBLEM TO BE SOLVED: To suppress the power energy required in stirring aeration treatment.
SOLUTION: The stirring aeration device 10 is equipped with the cylindrical body 22 inserted in a treatment tank 12 from an insertion port 13 to be immersed in a treatment liquid and the spiral blade 25 which is arranged in the cylindrical body 22 in a rotatable manner and to which the rotary drive force from a motor 21 is transmitted while decelerated by a speed reducer 26. Opening parts 22A and 22B are formed to the upper and lower ends of the cylindrical body 22 and an air supply port 30 is provided in the vicinity of the upper end opening part 22A. When air is sent into the air supply port 30 from the outside, air is guided into the cylindrical body 22. When the spiral blade 25 is rotationally driven by the motor 21, a liquid to be treated is stirred from the upper end side of the cylindrical body 22 toward the lower end side thereof and aerated by air to be sent out.