To solve a problem that it is difficult to apply each kind of former hydraulic turbine if effective head is 1 meter or less even if rich water flow quantity can be secured, and that high hydraulic turbine efficiency can not be expected even if the same is applied.

Energy contained in rich water flow quantity is utilized even if a head is small by using an oscillating vane hydraulic turbine. Torque can be efficiently provided and can be used as a rotary drive force source of a generator by making water flow move to a large water filler arranged in a casing side, a water drain port, and a large water passage port formed inside of the hydraulic turbine with acting on a vane body having large water flow pressure receive area under a sealed condition.