A method for manufacturing an electrical connection assembly includes a connector preparing step of preparing a connector (CN), in which each of plural terminals (20) has a conductor connection surface (27a) exposed outside an insulating housing (30). A connecting step of connects parts of conductors and the conductor connection surfaces (27a) corresponding thereto while tension is applied to a wiring material (10) by holding the wiring material (10) including the conductors arrayed at intervals from each other in an array direction at holding positions separated from each other in a longitudinal direction of the wiring material. A cutting step sandwiches and cuts the wiring material (10) by two cutting tools (62, 65) at a cutting position between one of the holding positions and the parts to be connected with the wiring material (10) kept held after the completion of the connecting step.