PURPOSE: To enable a positioning stoppage of high accuracy by giving a stoppage timing signal to an induction motor via the hard logic circuit equipped with a delay circuit.

CONSTITUTION: A position detector 19 is combined via a chain 17 to a turret shaft 13 and on a position detector 17, a rotary dog 21 for speed reduction and stoppage and a rotary dog 23 for detecting a station are respectively fixed freely rotatable. Therefore when a station position is detected by a sensor at the positive rotation time, and a speed reduction strobing signal is outputted, a speed reduction signal is outputted and when the strobing signal is then outputted, a stop command is outputted after the specified delay time from a hard logic circuit. The turret shaft 13 is thus positioned with high accuracy after the delay time based on the rise time of a strobing signal.