The invention relates to a locking device for the locking and/or unlocking of a component essential for the function of a vehicle with a casing, which more preferably serves for the fastening of the locking device to the component essential for the function and a moveable locking member, which can assume at least two positions, namely a locking position, in which the locking member protrudes from the casing through an opening and is actively connected with the component essentially for the function and an unlocking position, in which the locking member is not actively connected with the component essential for the function and an arresting part which in an arresting position arrests the locking member in the locking position in the event that the locking device is opened without authorization.To this end it is provided according to the invention that the arresting part is positively held in the arresting position.