A laundry treating apparatus includes a tub; a first drum disposed within the tub; a second drum disposed in the first drum and configured to couple to the first drum and to perform washing separately from the first drum; and a water discharge mechanism mounted on the second drum. The water discharge mechanism includes: a seat portion extending radially inwardly from a side wall of the second drum; a water receiving hole defined in the seat portion for receiving washing water from the second drum; and a water-discharging hole defined in the side wall for discharging washing water to an outside. The water discharge mechanism is configured to selectively flow washing-water into the discharge mechanism through the water receiving hole or discharge washing-water to the outside through the water-discharging hole, based on a magnitude of centrifugal force cause by rotation of the second drum.