The invention relates to an adjusting device (1) for rotor blades of a wind power plant, wherein an AC motor (3) is provided for adjusting the angle setting of the rotor blades. An input (23) serves for receiving an input alternating current (11). A frequency converter (2) is provided for generating a second alternating current (12) having a second frequency, wherein the second alternating current drives the AC motor (3). Additionally, a DC voltage source (4) and an inverter (5) are provided for converting the voltage provided by the DC voltage source (4) into an alternating current (13) for the AC motor (3). The inverter (5) is thereby separated from the frequency inverter (2).