PURPOSE: To provide the fitting structure of reinforcing members for automobile by which rigidity of rear wheel houses can be furthermore improved due to a performance rod, and deformation of the rear wheel houses can be always prevented regardless of the direction of load applied on the rear wheel houses so as to increase stability of operability.

CONSTITUTION: The end parts of a lower brace 13 constituting a subperformance rod 15 are respectively fitted and fixed to the upper part of a spring support 5 of left side and a rear floor 2, and the end parts of a lower brace 14 are respectively fitted and fixed to a spring support 6 of right side and the rear floor 2. Consequently, right and left rear wheel houses 4, 3 integrately formed with the spring supports 6, 5 can be individually prevented from the deformation by means of the lower braces 14, 13.