The sediment load and sediment budget in the Shirakawa River estuary were investigated for a period of one year. The cumulative suspended load during the flood period was 316 × 103 m3. The intertidal flat around the main tidal channel was composed of sand before the storm season, and the surface materials changed into silt and clay after flood discharge. The amount of deposited sediment was 424 × 103 m3 and the composition of silt clay was 57% (239 × 103 m3). The deposited fine sediment was eroded gradually by tidal current or wind-driven mixing. The resuspended sediment passed through the river mouth in the amount of 182 × 103 m3 during base-flow period. The net deposited volume was estimated to be 79 × 103 m3. The analyzed sediment budget suggests that the transport of fine sediment by the tidal cycle has a great impact on the morphodynamics of the estuary.