To provide a fuel tank arranging structure of a vehicle capable of lowering a seat height while securing the capacity of a fuel tank.

A fuel tank 12 is formed wider than the width of a main frame 4. Furthermore, a swollen part 12a extending downward is provided on one of tank bottoms (tank both edges) except for the bottom of the tank opposed to the main frame 4, i.e., at a tank bottom part 12b opposite to a swinging angle restraining part of an engine hanger link 7 across the main frame 4. Also, a fuel pump 13 pumping fuel to an injector is arranged in the swollen part 12a.