A substrate polishing apparatus includes; a platen including an upper surface configured to perform a polishing process on a semiconductor substrate, a slurry supply configured to supply slurry to the upper surface of the platen, wherein the slurry includes aqueous solution and abrasive particles, a collection pipe disposed under the platen and configured to guide the slurry, wherein the collection pipe includes a vertical guide pipe and a lateral guide pipe, a collection device disposed on an outer surface of the collection pipe, wherein the collection device includes an alternating arrangement of magnetic separators configured to separate the abrasive particles from the slurry using an electromagnetic force and sonicators configured to decompose the abrasive particles, and a collection tank connected to the collection pipe and configured to store the abrasive particles separated from the slurry by the collection device.