Abstract: A locking device is described for preventing the theft of a stringed instrument having a neck with a curved rear face and a planar front face. The locking device includes a rear arm having a curved inner face corresponding to the rear face of the neck, and a front arm having a planar inner face corresponding to the front face of the neck. The arms are hinged at their proximal ends so that the front arm is pivotal toward and away from the rear arm. Spaced axially aligned rows of padding projections extend inwardly from the inner faces of the arms. A lock releasibly joins the distal ends of the arms to lock the locking device around the neck of an instrument. A cable has a proximal end attachable in a groove between the hinged ends of the arms and a distal end attachable to a stationary object.