An apparatus for assisting carrying out exact hand movements, especially those performed by a surgeon during complex micro-surgical operations, comprising at least one support accommodated to the human arm or the hand. There is provided only a single upright column, one end of which is supported in a hinge joint equipped with a first brake device in order to obtain a free, braked mobility throughout a predetermined spatial region or zone with regard to the position and orientation thereof and at the other end such upright column carries the arm support. This arm support is mounted to be freely rotatable about the lengthwise axis of the upright column and is equipped with means located in the upright column for the continuous or infinite elevational adjustment of the upright column and thereby the arm support. There is also provided a second brake device for fixing the desired elevational position of the adjusted upright column and its arm support.