A clothes treatment apparatus comprising: a drum configured to accommodate an object to be treated; an air circulation flow path connected to a front opening and a rear opening of the drum to define a path through which air discharged from the front opening of the drum is introduced into the rear opening of the drum via a heat exchanger (1110, 1130); a base disposed below the drum and defining a space for mounting components constructing the air circulation flow path and the heat exchanger (1110, 1130); a circulation fan disposed at a downstream side of the heat exchanger (1110, 1130) based on a flow of air in the air circulation flow path and configured to generate a suction force to suck air in the air circulation flow path and supply the air to the drum; a water collection part having a bottom surface lower than a surrounding region on the base to collect condensate water generated from air circulating in the drum; a cover configured to cover the water collection part, and a trap formed in the water collection part to prevent external air from being introduced into the air circulation flow path via the water collection part due to the suction force of the circulation fan, and having a bottom surface lower than a surrounding region of the water collection part such that the condensate water is gathered therein, wherein the trap comprises: an upwardly-protruding rib (1351, 1352) protruding from the bottom surface of the trap toward the cover and having an upper end spaced apart from the cover; and a downwardly-protruding rib (1341, 1342) protruding from the cover toward the bottom surface of the trap and having a lower end spaced apart from the bottom surface of the trap; wherein the upwardly-protruding rib (1351, 1352) and the downwardly-protruding rib (1341, 1342) have a shape corresponding to a side surface of a cylinder, and are arranged to form concentric circles of different sizes, and wherein the upwardly-protruding rib (1351, 1352) and the downwardly-protruding rib (1341, 1342) are all provided in plurality, and are alternately disposed along a direction away from the center of the concentric circles. a drum configured to accommodate an object to be treated; an air circulation flow path connected to a front opening and a rear opening of the drum to define a path through which air discharged from the front opening of the drum is introduced into the rear opening of the drum via a heat exchanger (1110, 1130); a base disposed below the drum and defining a space for mounting components constructing the air circulation flow path and the heat exchanger (1110, 1130); a circulation fan disposed at a downstream side of the heat exchanger (1110, 1130) based on a flow of air in the air circulation flow path and configured to generate a suction force to suck air in the air circulation flow path and supply the air to the drum; a water collection part having a bottom surface lower than a surrounding region on the base to collect condensate water generated from air circulating in the drum; a cover configured to cover the water collection part, and a trap formed in the water collection part to prevent external air from being introduced into the air circulation flow path via the water collection part due to the suction force of the circulation fan, and having a bottom surface lower than a surrounding region of the water collection part such that the condensate water is gathered therein, wherein the trap comprises: an upwardly-protruding rib (1351, 1352) protruding from the bottom surface of the trap toward the cover and having an upper end spaced apart from the cover; and a downwardly-protruding rib (1341, 1342) protruding from the cover toward the bottom surface of the trap and having a lower end spaced apart from the bottom surface of the trap; an upwardly-protruding rib (1351, 1352) protruding from the bottom surface of the trap toward the cover and having an upper end spaced apart from the cover; and a downwardly-protruding rib (1341, 1342) protruding from the cover toward the bottom surface of the trap and having a lower end spaced apart from the bottom surface of the trap; wherein the upwardly-protruding rib (1351, 1352) and the downwardly-protruding rib (1341, 1342) have a shape corresponding to a side surface of a cylinder, and are arranged to form concentric circles of different sizes, and wherein the upwardly-protruding rib (1351, 1352) and the downwardly-protruding rib (1341, 1342) are all provided in plurality, and are alternately disposed along a direction away from the center of the concentric circles.