Vehicle body floor structure has a floor tunnel provided on a laterally central portion of a vehicle body floor panel and extending in a front-rear direction of a vehicle body, a desired stored component being stored in the floor tunnel. The stored component has a passageway formed therein to extend in a width direction of the vehicle body. The floor structure also has a cross member passed through the passageway of the stored component, the stored component is supported on the cross member via a resilient member, and the cross member is fixedly fastened at its opposite ends to the inner surfaces of opposed side walls of the floor tunnel.