PURPOSE: To reduce an accumulation error due to varying speed in a conveying process and improved the quality of a product by detecting the difference between the target time and the actually elapsed time and also the difference between the targed distance and the actually moved distance respectively and correcting the material conveying speed every moment.

CONSTITUTION: A measuring instrument 5 measures the present position of a conveyed material S through the output of a table motor M. When the arrival of the material S at the point A is detected from the output signals of the measuring instrument 5, timing signals P1 are generated by a timing generator 6 to start a time measuring instrument 7. Then, time signals T2 are outputted based on the time T2 after the material S passed the point A. The difference (the reamining time) between the signals T2 and the time T1 froma setting device 2 is calculated by means of a subtruction circuit 8. Also, the difference (the remaining distance) between the moved distance l2 outputted from the measuring instrument 5 and the moved distance l1 outputted from a setting device 1 is calculated by means of a subtruction circuit 9. Both the remaining time and the reamining distance as mentioned above are inputted in a setting device 3, and a set speed V1 is calculated to control the speed of rotation of a motor M.