A valve stem is journaled in a journaling portion of a valve box in an upwardly and downwardly movable manner; a packing is interposed between the journaling portion and the valve stem; a packing gland is arranged above the packing; a yoke sleeve is provided above the packing gland; and a valve seat in the valve box is opened and closed with a valve element provided at the lower end of the valve stem by rotating a handle fitted into the yoke sleeve to move the valve stem upward and downward. A protective tube formed integrally with the packing gland is provided between the packing gland and the yoke sleeve around the valve stem. A guide projection with which the inner periphery of the upper end of the protective tube comes into contact is provided on the lower surface of the yoke sleeve.