To integrally constitute a valve driving device and a valve by using at least a part of parts constituting the valve driving device and the valve as a unit.

In this rotary valve constituted by arranging a valve element in a valve casing turnably and attaching the valve driving device giving a driving force to a valve stem of the valve element to an upper part of the valve casing, a main body case of the valve driving device and a valve driving device mounting part of the valve casing are used in common to constitute the main body case of the driving device and the driving device mounting part of the valve casing as an integral member so as to dispense with the driving device mounting part provided in the valve casing.