Abstract: A butterfly valve of the type wherein a valve stem is prevented from sliding engagement with a valve seat is disclosed which assures more complete shaft sealing without causing any inconvenience to the controllability of the valve body and valve stem and can thus advantageously prevent fluid from leaking outwardly of a valve casing. A drive shaft rotatable and reciprocable in longitudinal directions of the valve stem is connected to an outer end of the valve stem. The valve casing extends so as to cover the drive shaft, and a packing member is disposed between the valve casing and the drive shaft to provide a shaft seal for the drive shaft. The rotation of and reciprocating movement of the drive shaft connected to the butterfly valve are performed by a simple drive mechanism. That is, the rotation of and the reciprocation of the drive shaft are accomplished only through rotation of a control shaft.