PURPOSE: To increase the working ratio of a bobbin processing system connecting multiple spinning frames spinning the yarns of different kinds and an automatic winder and circulating the bobbins fitted to trays for steaming.

CONSTITUTION: A steam set device is constituted of conveyance paths L1, L2 conveying filled trays to an automatic winder W from spinning framess, steam setters 1, 2 arranged in the middle, a conveyance path L8 conveying vacant trays to the spinning frames from the automatic winder W, and a branch path L9 branched from it and extended to this side of the steam setters 1, 2 on the filled tray conveyance paths L1, L2. When either spinning frame is stopped, the vacant tray of the kind corresponding to the spinning frame is sent to the branch path L9 from the vacant tray conveyance path L8.