To provide a joint structure of a hollow extrusion profile material with which in the case of joining the hollow extrusion profile material constituted of a vehicle structural plate, such as an electric car, and efficient manufacture reducing working man-hour and shortening the working time, can be obtained.

In the joint structure of the hollow extrusion shaped material joining both hollow extrusion materials constituted of two pieces of plane plates at the upper and the lower parts and plurality of ribs for connecting two pieces of plane plates, the side end parts of the respective profile materials 10, 20 have vertical ribs 14, 14 and also, one part side of the plane plates at the upper and the lower parts in both joining side end parts are joined with a force-fitting structure or an adhesive structure. Then, the other part sides have the structure for friction-stirring welding and further, the above force-fitting structure or the adhesive structure is constituted so as to become further strong with the pushing force F when the above friction-stirring welding is applied.