To mount a plurality of substrate monitoring sensors on a semiconductor substrate polishing device.

This polishing monitoring equipment 70 uses an index type polishing device constituting a substrate loading/unloading/finishing polishing stage (ps1) for polishing and washing a polishing stage by washing liquid and a rough polishing stage (ps2) for performing polishing by polishing agent slurry liquid. A CCD sensor 120a for monitoring the presence or absence of damage of a semiconductor substrate outer peripheral edge is mounted on a supporting arm 77 for oscillating a polishing pad of the ps1 stage. A substrate thickness measuring laser displacement sensor 120b is mounted on a rotary arm 110 provided to stand on a base 20 above a substrate holder table 70a constituting the ps1. A spectroscopic type photoelectric sensor 120c is mounted on the supporting arm 77 for oscillating a polishing pad 73' constituting the ps2 stage.