PURPOSE: To perform an effective vapor-liquid contact with concurrent stirring for liquid by spouting uniform and fine air bubbles by using a system in which the shape of the rotary blade directly connected to the rotary shaft of a motor is specifically designated and a hollow structure piercing through the inside of the rotary blade is provided.

CONSTITUTION: A rotary stirring blade 4 having a hollow part and leading to the hollow part of the motor 1 and its rotary shaft 2 of a vapor-liquid contact device is provided. And, the rear of the rotary stirring blade 4 is cut at a right anle to the direction of rotation, and a small hole 5 leading to the hollow part of the rotary stirring blade 3 is provided in the cut face 5. When an air intake pipe 6 is connected through the hollow part in this way, negative pressure part is produced right after the cut face 4 by rotation of the rotary blade 3, whereby effectively spouting uniform and fine air bubbles. Thus, the contact between vapor and liquid can be attained with high efficiency.