To provide a rotary device which can be driven more inexpensively than the conventional one while reducing risk caused by failure, and a circulation purification system using the same.

The rotary device includes: a rotary shaft; a plurality of shafts substantially radially disposed on the outer periphery of the rotary shaft; each bucket part provided at the tip of each of the plurality of shafts; each weight movably disposed along in the extending direction of each of the plurality of shafts; and each control means for executing movement control of each weight. Each weight installed corresponding to each of the plurality of shafts is gradually moved in one of a direction from the rotary shaft to the bucket part and a direction from the bucket part to the rotary shaft by the driving of each control means. The movement causes a unidirectional rotational moment in the rotary shaft and rotates the bucket parts together with the rotary shaft.