Abstract: A forest working machine, as well as a method for controlling the position of a knuckle boom crane during movements of the forest working machine, wherein the method comprises at least the following steps: driving the forest working machine, which comprises a front frame, a rear frame, a joint between said frames, allowing the swivelling of said frames in the lateral direction during the driving, a knuckle boom crane connected on the front frame to a swivelling device which makes it possible to turn said crane around the vertical axis and thereby to change its rotary position; changing the position of the forest working machine during the driving in such a way that the angular position between the front frame and the rear frame is changed; controlling said swivelling device automatically during the driving in such a way that when said angular position is changed, said rotary position is also changed, when said rotary position or its change is also dependent on said angular position or its change.