A washing method and a washing apparatus capable of obtaining a washing or cleaning effect by mechanical energy obtained by cavitation phenomena or nonlinear oscillation of micro air bubbles generated during the resonance of a multi-phase medium using low frequency waves. The resonance phenomenon becomes accelerated and uniform by virtue of the injection of air bubbles in the tub or the provision of a sonic or ultrasonic oscillation unit, thereby enabling a superior washing performance to be obtained. Since the present invention eliminates use of any pulsator, it is possible to considerably reduce the phenomenon that clothes get twisted or tangled. As a result, few damage of clothes is generated. Moreover, the electric power consumption in washing or cleaning is greatly reduced.