A device (2) for handling, mounting or demounting components (K, 5, 6, 7) of a wind turbine (1), in particular rotor blades (6) and/or a nacelle (7), with the aid of a crane (9) comprises a support (14) which can be connected to the crane (9) while being movable in the direction of a longitudinal axis (15) of said crane, and at least one guying device (16), preferably a guy cable (16a), which is connected at its first end to the movable support (14) and which can be connected by its second end to the component (K, 5, 6, 7) of the wind turbine (1) in order to stabilze the position of the component (K, 5, 6, 7) during handling and mounting. The guying device (16) is connected to the support (14) while being rotatable about the longitudinal axis (15) of the crane (9), preferably being rotatable through at least 90 degrees, more preferably being rotatable through at least 360 degrees, particularly preferably being rotatable through at least 380 degrees. In a method for handling, mounting or demounting components (K, 5, 6, 7) of a wind turbine (1), in particular rotor blades (6) and/or a nacelle (7), with the aid of a crane (9), the position of the component (K, 5, 6, 7) during handling and mounting or demounting is stabilized by means of at least one guying device (16), and the at least one guying device (16) is moved in the direction of a longitudinal axis (15) of the crane (9) during a vertical lifting movement of the component (K, 5, 6, 7). Before and/or during and/or after a vertical lifting movement of the component (K, 5, 6, 7), the at least one guying device (16) is rotated about the longitudinal axis (15) of the crane (9).