STRUCTURE FOR VEHICLE LOWER PORTION

To obtain a vehicle underbody structure that is capable of ensuring the capacity of a fuel tank while suppressing an increase in the size of the fuel tank. A fuel tank 32 is mounted behind a front floor 18 and under a center floor 20. An exhaust pipe 36 partially overlaps the fuel tank 32 when a vehicle 14 is seen in a plan view, and the exhaust pipe 36 is positioned between the fuel tank 32 and the center floor 20 at this overlapping section 3 6P.