A process and device for assembling a connector is provided, by which the production efficiency can be improved by preventing the problem of insertion error from occurring in a step of terminal insertion into a connector housing in the manufacturing process of the wiring harness by using an automatic assembly machine or in a step of the operation by the human hands. The process includes the steps of: provisionally locking the spacer in the connector housing; inserting a jig rod into the connector housing before inserting the terminal into the connector housing, the jig rod being for releasing the locking of the spacer which is completely locked in the connector housing; pulling the jig rod out from the connector housing; and inserting the terminal into the connector housing.