A wiring duct connection device includes a connection body to be inserted into an end portion of a wiring duct having conductors arranged on side walls within an elongated grove-like core along a longitudinal direction; contactors held in the connection body in such a manner that the contactors can protrude from opposite side surfaces of the connection body; and elastic bodies which biases the contactors outward. The elastic bodies are arranged side by side along the longitudinal direction at an inner side of each of the contactors, and each of the contactors includes convex contact portions that are one-piece formed at an outer end thereof, the contact portions being arranged along the longitudinal direction.