Abstract: In a method of and an apparatus for assembling units, incomplete units are moved forward along an assembly line, in progression, to successive stations for the addition of components to the unit until the unit is complete. Each unit, with machined parts, is disassembled at a disassembling station, provided with components including a specific part, and provisionally assembled as a whole at an assembling station. After the provisionally assembled units have been inspected as to a positional relationship of the components relative to one another, they are incorporated into a row of incomplete units so that one provisionally assembled unit is located after every incomplete unit and are disassembled at the disassembling station and, thereafter, reassembled again. During the second assemblage, the specific part is replaced with another specific part according to a result of the inspection so as to provide a predetermined positional relationship among the components, thereby completing the unit.