Abstract: An apparatus for generating microbubbles in water from a mixed fluid in which a gas and a liquid are mixed. The apparatus includes a cylindrical body which includes an inlet coupled to a hose, an outlet, and a cylindrical space section defined therein. The diameter of the space section is greater than each diameter of the inlet and the outlet. An inner container member is fixed in the space section such that a tubular passage is formed. A circular first collision section is provided on the inner container member. The mixed fluid that has been introduced through the inlet collides against the first collision section and is thus stirred. An “L” shaped second collision section is provided on the inner corner of the body adjacent to the outlet. The mixed fluid that has passed through the passage collides against the second collision section and is thus stirred.