Diameter more than 15μm provides bubble generation method and the bubble generating device capable of generating a large amount of tiny bubbles of less than 10μm in the liquid. A cylinder 2 in which one end and the other end at the closed end 14 has an open end 15, a rotary blade 3 using a rotating be in a cylinder 2 to cylinder 2 coaxially or substantially coaxially, the rotary vane 3 one sheet or two has more than two wings 4, the surface of the blade 4 is substantially parallel to the rotary shaft 5 axis of the rotating blade, the ventilation resistance between the cylinder inside and the outside air at the closed end 14 of the tube 2 has an inner diameter a 0.36 times the average width d of the blade is the 3mm vent 7 which is equal to or more than the flow resistance of the length, the portion of the open end 15 and the rotary vane 3 for at least the cylinder 2 into the liquid 20 soaked with the peripheral speed of the rotary blade 3, characterized in that rotates above 5.8 m / sec, a method and a bubble generating device for generating a minimum bubbles in the liquid.