A high pressure tank structure includes a high pressure tank, a pressure relief device, and a heat-resistant plate. The high pressure tank is capable of storing a fluid on an inside of a resin-made liner covered with a reinforced layer. The pressure relief device, when heated to a certain activating temperature, reduces an internal pressure of the high pressure tank. The heat-resistant plate is integrally attached to the high pressure tank, so as to be disposed facing the reinforced layer which is positioned at least on a bottom surface side when mounted in a mounting body.