Wire harness joint

The present invention relates to a wire harness joint for connecting harness within a vehicle such as motorcar and, particularly, to such a wire harness joint which can be reduced in thickness, disposed within the vehicle at any position and yet assembled in an easy and simple manner. The present invention provides a wire harness joint including a wiring circuit assembly and an insulation film or insulation films applied to the wiring circuit assembly, either on one or both sides. The wiring circuit assembly includes a number of flexible flat cables (FFC) disposed separately so that each one will not intersect another. The wiring circuit assembly further includes connections for connecting the tips of a wire harness that includes a plurality of parallel disposed FFCs to the FFCs of the wiring circuit assembly. Each of the insulation films is formed with windows at positions corresponding to the connections.