Disclosed is a connector for wiring in a vehicle that incorporates: a connector body consisting of either a male or a female connector attached to a terminal end of a harness; engagement projections formed on the periphery of the connector body and engaging with at least the two side edges of a hole in a vehicle panel; and a movable piece pressed into contact with the inside surface of the hole in the vehicle panel. Due to the repulsion spring force thereof, the movable piece thereby firmly engages the engagement projections with the hole in the vehicle panel.