the arm shaft 26 with a screw 32 a thread takeup rod 62 holding the thread takeup lever 15 and a needle bar crank 33 are mounted on the thread takeup crank 31 a connecting part 33a having u shaped section is formed at the extremity of the needle bar crank 33 when the sewing head 4 is joined to the arm 3 the connecting part 33a engages a needle bar stud 18a fixed to the needle bar 18 when rotated the arm shaft 26 drives the needle bar 18 for vertical reciprocation through the thread takeup crank 31 the thread takeup rod 62 and the needle bar crank 33 an annular indexing groove 40 is formed in a portion of the needle bar 18 projecting from the lower wall of the sewing head 4 and an indexing means or member 41 is attached to the lower surface of the sewing head 4 when power supply to the sewing machine 1 is stopped the sewing machine 1 stops with the needle bar 18 positioned at its top dead center in this state the indexing groove 40 of the needle bar 18 coincides with the indexing member 41 accordingly the needle bar stud 18a fixed to the needle bar 18 is able to engage the connecting part 33a of the needle bar crank 33 and the sewing.