PURPOSE: To exactly stop an upper shaft in a prescribed position regardless of sewing speed by effectively utilizing back electromotive force generated by a sewing machine for braking when the rotary phase of the upper shaft is a phase in a prescribed range.
CONSTITUTION: A notched part 58 of a prescribed open angle and a switching board 56 having an expanding part 60 are adhered to a rotary body 54 fixed to a sewing machine shaft 14. Two switches A and B are composed of the switching board 56 and terminals 67a, 68a and 69a, to which connecting lines L 4 , L 5 and L 6 brought into contact with this switching board are connected. Only when an activation stopping switch 40 is in a stop position S 2 and an upper shaft 14 is in the phase range corresponding to an above mentioned open angle 62, by these switches, a power source circuit 70 is opened and a control circuit 74 is opened. Then, when the upper shaft 14 goes to the prescribed position, a sewing machine motor 20 is exactly stopped by the back electromotive force generated in an internal part.