PURPOSE: To prevent occurrence of accidents beforehand by setting a plus α portion to the amount of feeding of a feeder and enabling to stop violent run of the feeder by comparing the set value with the present value of the feeder.

CONSTITUTION: A predetermined value is added to a value set to a feed setting digital switch 3. This added value is compared with the present value obtained from the amount of rotation of a motor by a comparator 5. When the present value exceeds above-mentioned added value, a stop signal is given, and the value set to the switch 3 is read at a fixed period and a value given to a command value register is subtracted. When this subtracted value exceeds a preset deviation value, a stop signal is transmitted. Occurrence of accidents can be prevented by this device.