In a hydraulic camshaft adjuster for a camshaft of an internal combustion engine, with an inner body connected for rotation with the camshaft and having at least one vane extending into a chamber formed in an outer body mounted rotatably relative to the camshaft and connected for rotation with a crankshaft for driving the camshaft and with a hydraulic control mechanism for adjusting the relative angular position between the inner and the outer bodies and including a locking structure for selectively locking and releasing the inner body with respect to the outer body, at least one bolt is slidably supported in an opening in the inner body so as to be movable into a guide slot in the outer body by the force of an axially acting spring element, said bolt when released from the guide slot against the axially acting spring force by the pressure force of a hydraulic operating fluid being retainable laterally displaced out of alignment with the guide slot by centrifugal forces against the force of a radially acting spring.