Abstract: An auxiliary device (6) for sewing up the starting end of a thread chain (F) in a chain stitch sewing machine (1) having a platform (2), a needle plate (3) and an edge cutter (4) comprises a suction and separating device (5) disposed subsequent to the needle plate (3) in sewing direction (N) for taking in and cutting off the thread chain (F) upon sewing a workpiece, a returning device for turning round the remaining end piece of the thread chain against the sewing direction (N), and a clamping and deflecting device disposed before the needle plate (3) in sewing direction for retaining the end piece of the thread chain turned round, and for laterally deflecting the same into the cutting area of the edge cutter (4).