A damage estimation device includes an acquisition unit that acquires a temperature change amount in a period during which an inflow air temperature rises and a period length, a distortion amount derivation unit that derives a distortion amount of a cooling device in the above period, based on the temperature change amount, and a damage value derivation unit that derives an accumulated damage value by integrating a value depending on the distortion amount. When the period length is shorter than a period length determination value, the distortion amount derivation unit derives a larger value as the distortion amount than when the period length is equal to or longer than the period length determination value.