A laundry treating apparatus, comprising: a housing; a first wash unit within the housing, the first wash unit comprising a first tub, a first drum mounted inside the first tub, and a first drive unit configured to drive a rotation of the first drum within the first tub; a second wash unit within the housing, the second wash unit being located at an upper side of the first wash unit and comprising a second tub, a second drum mounted inside the second tub, and a second drive unit configured to drive a rotation of the second drum within the second tub; a first detergent supply part for supplying a detergent and an auxiliary detergent to the first wash unit; a valve assembly that is configured to receive tap water and that is configured to control a supply of the tap water to each of the first wash unit and the second wash unit within the housing; and at least two supply lines configured to supply the tap water from the valve assembly to at least two supply points of the second tub in the second wash unit; wherein the housing comprises a tub case forming an exterior of the second wash unit, characterized in further comprising a second detergent supply part (470, 470d) for supplying a detergent and an auxiliary detergent to the second wash unit, wherein the tub case includes an inclined plane, wherein a tub cover for inserting laundry in the second wash unit and a detergent insertion door are formed on the inclined plane, the detergent insertion door being located in front of the tub cover, wherein the first detergent supply part and the second detergent supply part are located at a front side of the laundry treating device and the first detergent supply part is located in front of the second detergent supply part (470, 470d), and the second detergent supply part (470, 470d) is located under the detergent insertion door and configured to be exposed if the detergent insertion door is opened. a housing; a first wash unit within the housing, the first wash unit comprising a first tub, a first drum mounted inside the first tub, and a first drive unit configured to drive a rotation of the first drum within the first tub; a second wash unit within the housing, the second wash unit being located at an upper side of the first wash unit and comprising a second tub, a second drum mounted inside the second tub, and a second drive unit configured to drive a rotation of the second drum within the second tub; a first detergent supply part for supplying a detergent and an auxiliary detergent to the first wash unit; a valve assembly that is configured to receive tap water and that is configured to control a supply of the tap water to each of the first wash unit and the second wash unit within the housing; and at least two supply lines configured to supply the tap water from the valve assembly to at least two supply points of the second tub in the second wash unit; wherein the housing comprises a tub case forming an exterior of the second wash unit, characterized in further comprising a second detergent supply part (470, 470d) for supplying a detergent and an auxiliary detergent to the second wash unit, wherein the tub case includes an inclined plane, wherein a tub cover for inserting laundry in the second wash unit and a detergent insertion door are formed on the inclined plane, the detergent insertion door being located in front of the tub cover, wherein the first detergent supply part and the second detergent supply part are located at a front side of the laundry treating device and the first detergent supply part is located in front of the second detergent supply part (470, 470d), and the second detergent supply part (470, 470d) is located under the detergent insertion door and configured to be exposed if the detergent insertion door is opened.