A fuel tank (10) includes: a lower panel (12) made of steel and an upper panel (11) made of steel; and at least one pillar (100) made of steel which is disposed in an interior space (V) formed by the lower panel (12) and the upper panel (11) facing each other and of which a first end portion is fixed to the lower panel (12) and a second end portion is fixed to the upper panel (11) in a state where the second end portion is disposed in a hole formed in the upper panel (11).