A regular train of water waves can be generated with a vertically oscillating flow at a channel bottom. The solution of velocity potential for such flow-generated waves has been obtained, and expressions for wave profiles and bottom pressure are presented. Results of a small scale test for this type of wave generator show fair agreement with the theory developed : the generated wave heights being 80 per cent of analytical ones and the force required to drive an underwater piston being some 20 per cent larger than analytical ones. The reflection coefficient of the wave generator was also found to be 16 per cent in terms of wave height.
　Because of this low reflection coefficient, this type of wave generator is a very promising one to be fitted to an experimental wave tank which has benn troubled with the problems of multi-wave-reflection between the wave paddle and model structures under study.