In this study, we analyzed the assembly process of the following fitting systems from the aspect of cost: eccentric, inserted bolt lock, T, screw-mounting, screw-in type, and bracket and strip fittings. These are the most preferred fittings in the assembly of knockdown (KD) panel furniture. The fitting system with the least cost was sought. The direct labor, direct material, and direct energy costs, which are called the visible cost elements, were studied in the comparison. The stopwatch work measurement method was used to determine the periods of time needed for assembly. From this, the amounts of the cost elements were calculated. At the end of the analysis, the best fitting systems were determined as follows: 1) the eccentric fitting system was best for labor costs; 2) the screw-in type fitting system was best for material costs; 3) the inserted bolt lock and T fitting systems were best for the energy used during the assembly process; and 4) the screw-in type fitting system was best for the total visible costs. It would be appropriate to use the screw-in type fitting system for cabinets with doors, if the least cost is important, and provided that the consumer in the target market considers it to be suitable. It would be appropriate to use the eccentric fitting system if aesthetics are important, protruding parts are not wanted on the cabinet surfaces, and if a higher capacity is desired in the unit time period for the assembly of the panel furniture.