Toward achieving carbon neutrality, Mitsubishi Heavy Industries, Ltd. is working on the reduction of aircraft weight to improve fuel efficiency, thereby causing less environmental impact. One of the options for reducing the aircraft weight and the assembly time is the fusion bonding of thermoplastic composites. Of the bonding methods, resistance welding in which heating takes place only at the joining interface is addressed in this report, together with a summary of the newly developed process for ensuring weld quality.