To enable the action of each guide at nearly equal response speed even by using three or more mobile guides having different height levels.

This active yarn-feeding apparatus for a circular knitting machine is provided with 1st, 2nd and 3rd mobile guides corresponding to different level positions of feed wheels 16, 17, 18 in relation to 1st, 2nd and 3rd fixed guide means and a means for moving the 1st, 2nd and 3rd mobile guides at a nearly equal response speed. This means may be spring devices exerting different forces corresponding to the individual guide or a device produced by manufacturing the 1st mobile guide corresponding to the low level and the 3rd mobile guide corresponding to the high level with different materials and making the latter guide to be lighter than the former guide. The force of each spring device can be varied by changing at least one factor of the device selected from the shape, length, thickness and material.