PURPOSE: To provide possibility of making overall checking automatically and thereby enhancing effectiveness in works greatly by controlling each drive device or cutting device in a continuous cutting line for metal bands and thereby adjusting the cutting profile of the band.

CONSTITUTION: In this length measuring device 13 to measure the length of a sheet 11 sent from a cutting machine 9, image sensors 15W17 such as CCD camera, MOS camera, etc. are arranged in the positions mating to the leading and trailing edges on a conveyor 12 and a position to sense off sideways flow of the sheet 11 under the time of measurement in which a position detector 14 consisting of a photoelectric switch etc. senses the leading edge of the sheet 11. Then the sensors 15W17 measure the shape of the band, and each drive device in the continuous cutting line is controlled on the basis of result of comparing the measurements with the preset signal. Thus the cutting shape of the band is adjusted. According to this arrangement overall checking can be made automatically, that should assure enhancement of the effectiveness in works.