Abstract: An assembly method for an automotive engine and a transmission to provide a power unit. The assembly method is carried out as follows: The engine and the transmission are supported respectively on respective lifter tables which are controllably movable to change the location of the engine and the transmission in accordance with a location correction command fed thereto. The engine and transmission are provided at their joining faces with joining standards, respectively. Then, a pair of CCD cameras are inserted into between the joining faces of the engine and transmission to pick up the images of the respective joining standards. The thus picked-up images of the joining standards are processed by a processor to detect the positions of the joining standards and provide the location correction command to at least one of the lifter tables, so that at least one of the locations of the engine and the transmission is changed to cause the joining standards to coincide with each other.