To provide a microbubble generator that generate microbubbles in a structure in which a fixed outer blade, a rotary inner blade, and a shaft shape are devised, in the inside and outside a sealed container.

In the microbubble generator, use in both the inside and outside of a sealed container is made possible by changing a type of a bearing on a motor connecting side. Also, a gas flowing tube is attached to the shaft, constituting a structure in which the gas flows in the shaft. With a plurality of through-holes drilled in a part of a rotary inner blade, and with notching applied to the upper face, bottom face and outer periphery of a bearing installed on the shaft tip end side or, as a plurality of separate ideas, with use of a bearing made of a sintered metal having numerous pores inside as a material, the flowing-in of the gas is facilitated to minutely shear bubbles in the microbubble generator.