is provided at the free end part of the needle bar 44 in the neighbourhood of the needle 46 as shown in fig2 operation is as follows prior to the suturing operation the cover box 56 is removed from the l shaped frame 38 and the bobbin 59 carrying the thread 48n is mounted on the support pin 60 then the thread 48n is drawn out from the bobbin 59 and is passed through the hole 61a of the thread guide 61 and through the hole 38e of the l shape frame 38 and then the cover box 56 is attached again to the frame 38 the thread 48n is further passed through the hole 49a of the thread guide 49 and then is passed through the needle eye 46a of the curved needle 46 guided in the curved groove 46b thereof then the screw 55 fig2 is loosened to displace the stopper plate 54 from the slot 67c of the u shaped frame 67 and the shuttle holding member 51 is turned in the clockwise direction and then the shuttle 50 is placed in the chamber 67a so that the shuttle may be held there by the holding member 51 then the thread 48n which is finally passed through the needle eye 46a is knotted to the thread eye 50a of the shuttle 50 this thread is to be called a shuttle thread 48s as this if the needle thread 48n and the shuttle thread 48s are continuous these threads are not needed to be knotted at.