PURPOSE: To improve the reliability in holding of the substrate of a plurality of vacuum-suction substrate holding device which is annexed to an aligner.

CONSTITUTION: A first throttle valve 13, a first valve 7 and a first vacuum sensor 11 are arranged successively on one side of the vacuum line 5 which is communicated to the conveying chuck 1 distributed by a distributor 9 from the suction line 15 of a pump 10. Also, a second throttle valve 14, a second valve 8 and a second vacuum sensor 12 are arranged successively on the other vacuum line 6 which is communicated to a wafer chuck 2. A CPU 17 gives instructions to a controller 16 in such a manner that the detection suction surface pressure detected by the vacuum sensors 11 and 12 will be brought to the prescribed optimum suction pressure prescribed on the conveying chuck 1 and the wafer chuck 2, and the throttling quantity of the throttle valves 13 and 14 are changed through the above-mentioned controller 16.