A device protection apparatus comprising: a first sensor for detecting temperature of a refrigerant used for cooling a device including a heat-generation part generating heat by switching operation of a switching element; a second sensor for detecting temperature of the device; and a controller, wherein the controller is configured to: calculate a temperature difference (ΔT) between a first detected temperature detected by the first sensor and a second detected temperature detected by the second sensor, characterized in that the controller is further configured: to apply drive limitation to the device either when the temperature difference (ΔT) is higher than a predetermined temperature difference threshold value (ΔT _th) or when the temperature difference (ΔT) is lower than the predetermined temperature difference threshold value (ΔT _th) and the second detected temperature is higher than a predetermined first temperature threshold value (T _th1); and when the second detected temperature is higher than a predetermined second temperature threshold value (T _th2), to set an output power from the device at the time the increased second detected temperature reaches the second temperature threshold value (T _th2) as a maximum output power from the device. a first sensor for detecting temperature of a refrigerant used for cooling a device including a heat-generation part generating heat by switching operation of a switching element; a second sensor for detecting temperature of the device; and a controller, wherein the controller is configured to: calculate a temperature difference (ΔT) between a first detected temperature detected by the first sensor and a second detected temperature detected by the second sensor, characterized in that the controller is further configured: to apply drive limitation to the device either when the temperature difference (ΔT) is higher than a predetermined temperature difference threshold value (ΔT _th) or when the temperature difference (ΔT) is lower than the predetermined temperature difference threshold value (ΔT _th) and the second detected temperature is higher than a predetermined first temperature threshold value (T _th1); and when the second detected temperature is higher than a predetermined second temperature threshold value (T _th2), to set an output power from the device at the time the increased second detected temperature reaches the second temperature threshold value (T _th2) as a maximum output power from the device. to apply drive limitation to the device either when the temperature difference (ΔT) is higher than a predetermined temperature difference threshold value (ΔT _th) or when the temperature difference (ΔT) is lower than the predetermined temperature difference threshold value (ΔT _th) and the second detected temperature is higher than a predetermined first temperature threshold value (T _th1); and when the second detected temperature is higher than a predetermined second temperature threshold value (T _th2), to set an output power from the device at the time the increased second detected temperature reaches the second temperature threshold value (T _th2) as a maximum output power from the device.