Observed for the first time was strange behavior of an ultrasonic wave called ``coherent backscattering'' from inhomogeneous media. This effect is theoretically expected to occur as a result of a weak localization of waves propagating in a medium with many scatterers. It is a general nature of all kind of waves and has actually been confirmed for the optical waves. The ultrasonic wave incident to the dispersion system of small particles is scattered by the difference in the mechanical impedance in the system, whose intensity profile has a peak in the backscattering direction with respect to the incident wave. The peak height is expected to be twice as intensive as that of the diffuse scattering. The stroboscopic Schlieren image of the ultrasonic propagation scattered by the dispersion of polystyrene particles 100 (mu)m in diameter was obtained and an intensive component going back the same way as the incident light was found. The quantitative measurement of the scattering profile was also carried out by a laser diffraction method and the result obtained shows good agreement with the theoretical prediction, giving a peak factor of 2. This phenomenon would be important when treating ultrasonic waves in inhomogeneous systems such as human organs.