A laundry treating apparatus is disclosed. The laundry treating apparatus includes an outer case defining an appearance of the laundry treating apparatus, a washing tub arranged in the outer case, to receive laundry, a top lid mounted to a top of the outer case such that the top lid is openable and closeable, and an air flow assembly mounted to the top lid, to stepwise adjust a size of a passage communicating an interior of the outer case and an exterior of the outer case. The laundry treating apparatus can prevent moisture from staying in the interior of the laundry treating apparatus for a prolonged period of time, thereby preventing a failure of the laundry treating apparatus, generation of an offensive odor and propagation of bacteria in the interior of the laundry treating apparatus.