To improve the installation workability and installation position precision in connecting adjacent building units.

This connecting method for building units 2 includes a process for inserting the spacer 12 of a joint plate 10 into the gap between adjacent building units 2, a process for coupling the coupling hole sections 14 of the joint plate 10 with the coupling sections (stud bolts 5) on the upper faces of the adjacent building units 2, a process for allowing the guides 13 of the joint plate 10 to about on the side faces of the adjacent building units 2, and a process for fixing the plate-like member 11 of the joint plate 10 to the upper faces of the adjacent building units 2.