This paper presents an experimental approach to investigate the accumulation process of cedar at the bridge. Recently, it was frequently observed the river floods had brought a lot of woody debris such as beech trees along its way and deposited at the bridge locations as for an example during the Typhoon No. 10 in August 2016 in Omoto River, Iwate Prefecture. The rise of the water level due to wood accumulation at the bridge not only destroys the bridge itself but also causes local flooding. It was a possibility of similar disaster in Akita Prefecture which has a lot of cedars. In this study, a series of hydraulic experiment models were carried out using a bridge model with a scale of 1/180 that based on the actual width and the river channel of Omoto River. The cedar rod was used for driftwood model. Three experiment cases were conducted to investigate the effects of driftwood length, driftwood mixing length and flow rate. The number of driftwood was estimated from the volume of measured driftwood during the flood event in Omoto River. As results, this study indicated that the length of driftwood plays an important role to the amount of debris accumulation at the bridge and water level changes in surrounding areas.