In a vehicle floor structure, a subsidiary frame is provided between a front frame and a seat frame and at a position higher than a lower frame, for supporting thereon a floor section. Step support frame is provided laterally outwardly of the lower frame, for supporting thereon a boarding step so that the floor section is located at a level higher than the boarding step. Vehicle body frame structure includes, for each of left and ride side sections of the vehicle, a straight vertical frame to which are mounted the respective ones ends of an upper arm, lower arm and cushion unit, and respective mounting sections for the upper arm, lower arm and cushion unit can be provided in linear alignment with one another in the straight vertical frame along the length thereof