interlinked with itself on the side of the workpiece 3 facing the looper 2 and the needle plate 4 the looper 2 comprises a blade 21 which is pointed at the front end a thread guiding surface 22 disposed in a region of the blade 21 facing the looper shaft 16 a thread driving device 23 formed adjacent to the thread guiding surface 22 and a thread retaining device 24 disposed in a region of the blade 21 facing the needle plate 4 which thread retaining device is formed as a retaining step 25 the looper 2 is disposed in such a way as to be able to pivot and to be displaced about a movement path 26 of the sewing needle 7 a double arrow 27 clearly indicates the feed directions of the feed path of the looper shaft 16 and of the looper 2 fig2 illustrates the looper 2 in its thread receiving position in comparison to fig1 the sewing needle 7 has moved on its needle path 26 in a curve towards the left and in so doing enlarged the loop 18 since the sewing thread 8 is retained in the workpiece 3 the thread driving device 23 which entrains the sewing thread 8 and the loop 18 in a downwards direction is provided with a thread driving device surface 28 against which the sewing thread 8 coming from the sewing needle 7 is supported the thread driving surface 28 extending diagonally to the blade 21 and a retaining surface 29 extending likewise diagonally to the blade 21 facilitate the formation of a so called thread triangle 31 as illustrated in fig3 which is.