A polishing apparatus capable of monitoring an accurate progress of polishing is disclosed. The polishing apparatus includes: a polishing table for supporting a polishing pad; a table motor configured to rotate the polishing table; a top ring configured to press a substrate against the polishing pad to polish the substrate; a dresser configured to dress the polishing pad while oscillating on the polishing pad during polishing of the substrate; a filtering device configured to remove a vibration component, having a frequency corresponding to an oscillation period of the dresser, from an output current signal of the table motor; and a polishing monitoring device configured to monitor a progress of polishing of the substrate based on the output current signal from which the vibration component has been removed.