An emergency isolation valve has a valve plug in a valve body connected to a pipeline. The valve plug is connected to a valve shaft around which a sector gear is provided and engaged with a rack of a piston rod in a cylinder. The piston rod has a piston at one end and is connected to a compression spring at the other end. The piston is moved by air supplied into a cylinder from a compressed air source via a fluid control and a solenoid selector valve. Air supply stops and a discharge hole of the cylinder is opened, so that air is discharged to the outside. The piston is returned by the compression spring to close the discharge hole. At the same time stop of the piston rod is detected by a sensor thereby checking whether to actuate the valve plug normally even during operation.