the resistor 14 is short circuited and the trigger voltage applied to the gate electrode of the thyristor 3 reduces to zero the trigger voltage setting means is thus rendered ineffective thereby to turn off the thyristor 3 upon the turn off of the thyristor the motor 4 immediately stops rotating thereby keeping the needle bar stationary at the upper designated position under this condition the hartley type oscillator continues to fail to oscillate and the transistor 20 is kept in cut off state therefore the transistor 16 continues to conduct rendering the trigger voltage setting means ineffective continuously the needle bar is thus maintained at the upper designated position in other words in the absence of depression of the controller 5 if the needle bar is at the upper designated position with the main switch 2 closed the motor 4 remains stationary thus holding the needle bar at the upper designated position while if the needle bar is not situated at the upper designated position the motor 4 rotates slowly until the needle bar reaches the upper designated position so that when the needle bar reaches the upper designated position the motor 4 stops immediately thus holding the needle bar at the upper designated position now reference is made to the case where the controller 5 is depressed fully with the needle bar at the upper designated position in this case upon the depression of the controller the divided voltage.