A compressed air energy storage power generation device includes an inert gas source for supplying an inert gas, an inert gas flow path system, and a flow path switching unit. The inert gas flow path system fluidly connects the gas phase portion of the high temperature heat storage unit, the gas phase portion of the low temperature heat storage unit, and the inert gas source. The flow path switching unit switches the inert gas flow path system to at least a state in which the inert gas source is in communication with both the high temperature heat storage unit and the low temperature heat storage unit and a state in which the inert gas source is blocked from both the high temperature heat storage unit and the low temperature heat storage unit.