A stack-type laundry treating apparatus comprising: an upper treating apparatus including: an upper cabinet including an upper side panel defining an upper side appearance thereof, and an upper base panel defining a bottom thereof; a drying drum rotatably disposed in the upper cabinet, wherein a drying target is inserted into the drying drum; an upper driver for rotating the drying drum; and an air flow path for supplying and discharging air to and from the drying drum, a lower treating apparatus including: a lower cabinet including a lower side panel defining a lower side appearance thereof, wherein a top of the lower cabinet is covered with the upper base panel; a tub disposed in the lower cabinet, wherein washing-water is stored in the tub; a washing drum disposed inside the tub, wherein a washing target is inserted into the washing drum; and a lower driver for rotating the washing drum; and aligning legs located inwardly of the upper side panel and the lower side panel and coupled to the upper base panel, wherein when the upper treating apparatus is mounted on the lower treating apparatus, aligning legs align a mounted position of the upper treating apparatus along the lower side panel, wherein the aligning legs are coupled to the upper base panel inwardly of the upper base panel, wherein the aligning legs include at least one pair of aligning legs disposed on each of both sides of the upper base panel, wherein the aligning legs are seated so as to slide forwards or rearwards along the lower side panel; and characterized in that a rail frame is disposed on a top of the lower side panel, wherein at least one of the aligning legs is in contact with the rail frame and is configured to slide along the rail frame in a front and rear direction. an upper treating apparatus including: an upper cabinet including an upper side panel defining an upper side appearance thereof, and an upper base panel defining a bottom thereof; a drying drum rotatably disposed in the upper cabinet, wherein a drying target is inserted into the drying drum; an upper driver for rotating the drying drum; and an air flow path for supplying and discharging air to and from the drying drum, an upper cabinet including an upper side panel defining an upper side appearance thereof, and an upper base panel defining a bottom thereof; a drying drum rotatably disposed in the upper cabinet, wherein a drying target is inserted into the drying drum; an upper driver for rotating the drying drum; and an air flow path for supplying and discharging air to and from the drying drum, a lower treating apparatus including: a lower cabinet including a lower side panel defining a lower side appearance thereof, wherein a top of the lower cabinet is covered with the upper base panel; a tub disposed in the lower cabinet, wherein washing-water is stored in the tub; a washing drum disposed inside the tub, wherein a washing target is inserted into the washing drum; and a lower driver for rotating the washing drum; and a lower cabinet including a lower side panel defining a lower side appearance thereof, wherein a top of the lower cabinet is covered with the upper base panel; a tub disposed in the lower cabinet, wherein washing-water is stored in the tub; a washing drum disposed inside the tub, wherein a washing target is inserted into the washing drum; and a lower driver for rotating the washing drum; and aligning legs located inwardly of the upper side panel and the lower side panel and coupled to the upper base panel, wherein when the upper treating apparatus is mounted on the lower treating apparatus, aligning legs align a mounted position of the upper treating apparatus along the lower side panel, wherein the aligning legs are coupled to the upper base panel inwardly of the upper base panel, wherein the aligning legs include at least one pair of aligning legs disposed on each of both sides of the upper base panel, wherein the aligning legs are seated so as to slide forwards or rearwards along the lower side panel; and characterized in that a rail frame is disposed on a top of the lower side panel, wherein at least one of the aligning legs is in contact with the rail frame and is configured to slide along the rail frame in a front and rear direction.