A laundry treating apparatus includes a tub configured to hold wash water, a drum rotatably supported in the tub and including a shaft disposed perpendicular with the ground, and a sub-drum detachably mounted to the drum and configured to wash laundry independently from the drum. The sub-drum includes a discharging area in which a discharging path is defined to selectively discharge the wash water in the sub-drum by a centrifugal force generated by rotation of the sub-drum. A check valve is included in the discharging area and is configured to selectively open and close the discharging area when acted on by an external force applied by the centrifugal force generated by the rotation of the sub-drum.