A first gap (28) to be eliminated at the time of a compressive deformation of a fuel-tank main body (14) is formed between a lower-side reinforcing member (18) and an upper-side reinforcing member (20) in a fuel-tank main body (14). A second gap (40) to be eliminated at the time of an expansion deformation of the fuel-tank main body (14) is formed between an opposed member (30) of the lower-side reinforcing member (18) and the upper-side reinforcing member (20).
