An apparatus for rotatably mounting a rotor to be balanced is provided. The apparatus include a rotatably mounted balancing spindle to which the rotor to be balanced is to be non-rotatingly connected, at least one bearing block, a plurality of spring bars aligned parallel to the spindle axis and used to mount the balancing spindle on the bearing block such that the balancing spindle is able to vibrate, and a drive mechanism for the balancing spindle. The spring bars are arranged in more than two planes at different distances from the spindle or in planes having different rotary angular positions about the spindle axis.