In the Kikuchi River, which is located in the northern part of Kumamoto prefecture, sediment deposition at the estuary has become a serious social problem in recent years. In this study, in order to asses the present situation of sediment transport in the Kikuchi River estuary, the flow velocity was measured along the water-route and across the river by an Acoustic Doppler Current Profiler (ADCP) during spring tide. Furthermore, an automatic water sampler was placed on the river bank to extract suspended solids and nutrient salts from the stream water. The results showed that flow velocity was transversely uniform at flood tide. Furthermore, the transport of the suspended solids was activated in the period of the strongest flood current.