An assembly method of a laundry treating apparatus includes a first step of positioning a second treating apparatus in a desired place for assembly, a second step of seating a first treating apparatus on the second treating apparatus, a third step of coupling a upper fastening unit of the second treating apparatus with a lower portion of the first treating apparatus, and a fourth step of coupling a control panel onto a panel seating portion provided between a lower surface of a first front panel of the first treating apparatus and an upper surface of the second front panel of the second treating apparatus. The upper fastening unit may be positioned to be higher than a lower surface of the first treating apparatus after the second step is performed.