A micro-bubble generator, etc. capable of efficiently generating bubbles having a bubble diameter of nanometer order.A micro-bubble generator is provided with a swirl chamber, a fluid introduction opening which is connected to the swirl chamber and introduces fluid along a line tangent to the inner surface of the swirl chamber, and a discharge tube which guides the fluid in the direction substantially perpendicular to the direction in which the fluid is introduced. The discharge tube penetrates through the wall surface of the swirl chamber and protrudes to the inside of the swirl chamber. The configuration isolates the path of the introduced fluid, and this can reduce a loss of the kinetic energy of the swirl flow of the fluid. As a result, the sizes of the generated micro-bubbles can be reduced.
