To relate the lower part of a vehicle body to the upper part to significantly improve the body rigidity as a whole.

A tunnel part 24 is formed in the lateral center of a floor panel 1, and a floor frame 31 longitudinally extending to constitute a closed sectional structure is provided along the tunnel part 24. A roof frame 44 extending long over a front header part 41 and a rear header part 41 and constituting a closed section is provided in the lateral center of the inner surface of a roof panel 2. The rear end of the floor frame 31 is connected to the rear end of the roof frame 44 through a vertically extending gazette member 50.