The device measuring micro-nano bubbles whose diameters were from 1 to 10 micrometer was developed. The bubbles were visualized by a close-up photographing and image processing system with high magnification microscope. The floating velocity of the bubbles as a physical characteristic was measured by using the system. The velocity of micro-nano bubbles does not depend on Stokes' law. The micro-nano bubbles were observed in not only tap water, but also distilled water and seawater.
