A camshaft adjuster (10) for an internal combustion engine which includes a locking mechanism is provided. At least one locking element (21, 22) which can be locked in the zone of a central position (20) as well as at least one additional locking element (23, 24) that can be locked in the zone of a retarded end position (19) or an advanced end position (20) are provided such that the internal combustion engine can be selectively started from an end position (19, 20) or the central position.