A fuel tank structure includes: a fuel tank that is installed in an automobile and that accommodates fuel; a bag-shaped member that is fixed to a ceiling portion of an interior of the fuel tank, and whose state of contact with a liquid surface of fuel accommodated in the fuel tank is maintained due to the bag-shaped member inflating or deflating in accordance with a height of the liquid surface; a temperature sensor that senses a temperature of the fuel or evaporated fuel that is within the fuel tank; and a cooling wind introducing section that introduces cooling wind into an interior of the bag-shaped member in a case in which the temperature of the fuel or the evaporated fuel detected by the temperature sensor becomes higher than a predetermined temperature.