A camshaft adjuster for an internal combustion engine with a locking element is provided. For adjusting the camshaft adjuster (1) in the direction of a locking position, for example, when the internal combustion engine is switched off or when the hydraulic pressure drops, a mechanical spring element (23) is located between the rotor (5) and stator (3). The mechanical spring element (23) is arranged in a pressure chamber (12; 13). In this way, the installation space already existing for the pressure chambers (12; 13) can have a multifunctional use.