A tension springs separation device for use in a system for automatically mounting tension springs to a seat frame of a seat for an automobile. In the separation device, there are provided two narrow portions in a feed passage in a part feeder, each of which has a width permitting only one tension spring to pass therethrough in the longitudinal direction, and there are provided two projected ramp portions each of which has a level difference slightly larger than the outside of the tension spring, whereby a large number of tension springs loaded into the part feeder can be sent out one by one sequentially.