A camshaft adjuster (1) including a stator (2) and a rotor (4), a spring (6) tenses the rotor (4) rotationally counter to the stator (2). According to the invention, the spring is a coil spring (6), the stator (2) includes a first recess (8) of a first free end (10) of the coil spring (6) and the rotor (4) includes a second recess (12) for a second free end (14) of the coil spring (6).