Though the local scour take rise by change of sediment transported through each section, generally, it is so complex phenomenon that the change of flow character in scour hole is closely related to progress of scour, and the development of scour is defined by changed flow charactor. According to investigation on the sediment motion and the flow character by observations with moter-drive camera, on the scour mechanism, the progress of local scour from submerged plane jets are distinguished in three stage