A device for adjusting a rotational angle relationship between a camshaft and its drive element, comprising two circular segment shells provided on the drive element together with an interposed part forming two working spaces therebetween. The both shells are connected to one of the camshaft and the drive element, and the interposed part being connected to the other of the cam shaft and the drive element while the circular segment shells being movable relative to the interposed part in a setting action such that during adjustment in the setting direction the circular segment shells are adjusted so that the volume enclosed in a first one of the working spaces increases while the volume enclosed in a second one of the working spaces decreases. Each of said working spaces are connected to a first setting pressure medium source separately via a non-return valve which opens toward a respective one of the working spaces, and the working spaces can be directly connected to one another by means of a control valve. A third circular segment shell is provide and forms with a first one of the circular segment shells a third working space for an additional adjustment of the rotational angle relationship.