A rotation drive device composing: a rotating shaft which is pivotally supported to a stand; a rotating table which is fixed onto the rotating shaft; a plurality of rotating units which are provided at a plurality of positions spaced along a rotating direction on the rotating table; each of the rotating units including a support table which is supported to the rotating table, and a weight which is supported to the support table, the rotation drive device changing a radial position of the weight in each of the rotating units and rotating the rotating table and the rotating shaft on the basis of a fluctuation of a rotating moment which a gravitational force acting on the weight applies around the rotating shaft, wherein each of the rotating units has a swing arm which is supported so as to be swingable around a swing center axis provided in the support table, wherein a fluid cylinder is attached to the support table and makes the radial position of the weight with respect to the rotating shaft controllable; the rotation drive device changes the radial position of the weight in each of the rotating units by sequentially supplying a fluid from a fluid supply source to the fluid cylinder of each of the rotating units, characterized in that the weight is provided at a position at which a length of an arm of the swing arm from the swing center axis is longer, and a connection point in the fluid cylinder side is provided at a position at which the length (r) of the arm from the swing center axis is shorter, and that the support table provided with the swing center axis of the swing arm is supported so as to be swingable around an oscillation support axis which is provided in a base table attached to the rotating table and is orthogonal to the rotating shaft, and the swing center axis of the swing arm provided in the support table is swingable at a fixed angle to a side to which a gravitational force acting on the weight is applied, among both sides with respect to a neutral position positioned on a surface which is orthogonal to the rotating shaft. a rotating shaft which is pivotally supported to a stand; a rotating table which is fixed onto the rotating shaft; a plurality of rotating units which are provided at a plurality of positions spaced along a rotating direction on the rotating table; each of the rotating units including a support table which is supported to the rotating table, and a weight which is supported to the support table, the rotation drive device changing a radial position of the weight in each of the rotating units and rotating the rotating table and the rotating shaft on the basis of a fluctuation of a rotating moment which a gravitational force acting on the weight applies around the rotating shaft, wherein each of the rotating units has a swing arm which is supported so as to be swingable around a swing center axis provided in the support table, wherein a fluid cylinder is attached to the support table and makes the radial position of the weight with respect to the rotating shaft controllable; the rotation drive device changes the radial position of the weight in each of the rotating units by sequentially supplying a fluid from a fluid supply source to the fluid cylinder of each of the rotating units, characterized in that the weight is provided at a position at which a length of an arm of the swing arm from the swing center axis is longer, and a connection point in the fluid cylinder side is provided at a position at which the length (r) of the arm from the swing center axis is shorter, and that the support table provided with the swing center axis of the swing arm is supported so as to be swingable around an oscillation support axis which is provided in a base table attached to the rotating table and is orthogonal to the rotating shaft, and the swing center axis of the swing arm provided in the support table is swingable at a fixed angle to a side to which a gravitational force acting on the weight is applied, among both sides with respect to a neutral position positioned on a surface which is orthogonal to the rotating shaft.