It is an object to improve the reliability of a temperature adjusting device which cools an in-vehicle device such as a battery by using a refrigerant. A device temperature adjusting device 61 that is an in-vehicle device temperature adjusting device adjusts the temperature of a battery 55 mounted on a vehicle and includes a refrigerant circuit R having a compressor 2 which compresses a refrigerant, an outdoor heat exchanger 7 for letting the refrigerant radiate heat, and a refrigerant-heat medium heat exchanger 64 for cooling the battery 55 by letting the refrigerant absorb heat, and a control device 11. The control device 11 stops the compressor 2 on the basis of the fact that the refrigerant circuit R is blocked.