the invention relates to a roof structure of a motor vehicle , comprising a front roof cross member and an intermediate roof cross member located behind the front cross member , said cross members extending in the transverse direction of the vehicle , the structure also comprising an equipment support connecting these cross members to one another approximately in the middle thereof , the support has , at a first end , indexing means that penetrate in the longitudinal direction of the vehicle into corresponding orifices provided in one of the cross members , these indexing means carrying out positioning in the transverse and vertical directions , while the first end cooperates in a bearing manner in the longitudinal direction with a vertical flank of said cross member , and the support has , at a second end , clip - fastening structures that carry out pre - retention in the vertical direction with the other cross member .