To provide an operation device equipped with a mobile body making rotational movement which keeps visual curing effectiveness and can be used as an intellectual training material about relation between fluid flow and motion.

The device has at least one mobile body 10 which is fixed in a position predetermined distance apart from a rotary shaft 30 so that it can rotate around the rotary shaft and a propulsion generating means 16 which is set in fluid stream, generates propulsion and is installed up within predetermined angle range to the mobile body so that it can rotate. At least one mobile body is located in the fluid stream, propulsion which generates propulsion generating means in the mobile body arises, at least one mobile body rotates from an end towards another end within predetermined angle range and continuously rotates around the rotary shaft so that the propulsion generating means can continuously generate the propulsion when the propulsion generating means is located at a predetermined angle to the direction of the fluid flow.