A body shell structure of a motor vehicle includes a side superstructure of the body shell defining on either side of the vehicle two recess portions for wheel arch housings of the vehicle connected by a floor of the vehicle. The body shell structure includes, in each of the two recess portions for wheel arch housing, a wheel arch housing part and at least one mount for attaching the rear shock absorber, assembled by edges thereof to each of the wheel arch housing parts. The wheel arch housing part defines at least one substantially oblique surface portion around and beyond the edges of the mount. The superstructure also includes a structural plate rigidly connected to an oblique surface portion of the wheel arch housing part and secured to a substantially vertical surface portion of the superstructure.