A safety device for the throttle operation includes a shaft, a linking plate having an end connected and moving with the shaft and another end provided with an projecting bent wing, a pulling plate having one end formed with a shaft hole for combining with the shaft and located at a side of the bent wing and another end resting on an end surface of the bent wing and connected with a throttle line. The bent wing moves the throttle line to move the pulling plate for an angle for opening the throttle. The safety device further includes a contact switch for contacting the linking plate so an engine control system may be electrified by the contact switch to reduce its speed to a slow condition even if the throttle line is stuck immovable and unable to return to its original position after pulling open the throttle, keeping safe a vehicle.