It is important to separate and collect particles from solid-liquid mixture in order to reduce in environmental load and treatment cost of waste fluid. In this study, we try to separate and collect particles from the mixture by ultrasonic waves with relatively low frequency. In present report, we use garnet as removal particles. The particles are fully stirred in test water and then ultrasonic waves are irradiated with some frequencies. The particles behavior observed by a high-speed video camera is analyzed by a time series image analysis and correlated with sound pressure distribution.