A cable position monitoring device is provided, for monitoring the position of a cable guided in the rollers of a roller assembly of a cable operated transportation system comprising at least one first and at least one second cable roller defining a reference roller, the cable position monitoring device comprising a movement-magnitude detecting device for determining a first movement-magnitude of the at least one first cable roller and a second movement-magnitude of the reference roller, and an evaluating device for comparing the first and second movement-magnitudes and for determining a mutual movement-magnitude deviation between the first and second movement-magnitudes which corresponds to a safe-to-operate status of the transportation system. An improved cable operated transportation system as well as a method for monitoring the position of a cable of a cable operated transportation system are also provided.