A device for guiding a conveyor belt, having a guide unit with an outer and an inner hollow-cylindrical body, the inner hollow-cylindrical body having a first central axis and being arranged in the outer hollow-cylindrical body, which has a second central axis, and both hollow-cylindrical bodies each have a central axis, with at least one bearing for rotatably mounting the outer hollow-cylindrical body on the inner hollow-cylindrical body and with an articulation body designed for mounting the inner hollow-cylindrical body on a central axle, wherein the articulation body is further designed to allow a horizontal and/or vertical change in angle of the first and/or second central axis relative to a central axis of the central axle. In order to increase the service life of the conveyor belt, the device is equipped according to the invention with a measuring and evaluating system including a sensor unit arranged inside and/or outside the guide unit, wherein the measuring and evaluating system is designed to detect the change in angle. The invention is based on the consideration that from a control behavior of the device, the causes of a fault of the belt run can be identified, deduced or narrowed down. Furthermore, a system for monitoring and guiding a conveyor belt using a device according to the invention is described.