In the case where soft bottom mud with high water content is fluidized by wave-induced pressure, cracks are generated in the surface of the mud. In order to examine the behavior of sandy mud under wave action, a laboratory experiment has been conducted in a condition that sediment is fluidized and cracks are generated in the surface. It is found that water content of sandy mud is remarkably decreased under wave action by not only consolidation but washout of clay particles, which contain significant amount of water, from the mixture sediment. The characteristics of sediment transport of sandy mud are clarified in comparison with the experimental results on genuine mud reported by a conventional study. Also, it is found that resonant fluidization response occurs in sandy mud causing energy dissipation of surface waves.