Preparation is made of first and second contact assemblies in each of which ends of a plurality of contacts are respectively coupled to a plurality of coupling portions of a carrier. The coupling portions of at least one of the first and second contact assemblies are bent so as to offset the contacts in a thickness direction of the carrier. Then, the first and second contact assemblies are combined together in a state where the carriers overlap each other and the contacts are aligned with and spaced apart from each other in the same plane. After integrating the contacts, the coupling portions are cut off. Then, the integrated contacts are collectively inserted into a shell.