This paper shows bubbly flow characteristics measured of standing flow and unsteady flow in a Venturi tube. As for the standing flow characteristics, the distribution of pressure and void fraction are measured. Using the equation of sound velocity in adiabatic isentropic, the shock waves occurs at the point of transition from supersonic flow to subsonic flow, and the bubbles are collapsed at the same area. As a non-steady phenomena, by performing visualization and synchronous measurement of pressure, the presence of propagating pressure wave caused by bubble collapse. The bubble diameters generated by using this device showed a tendency to be further miniaturized under both condition that a shock wave is generated and a pressure wave is generated.