A determination device able to determine a cause of generation of gas with a simple configuration is provided. The determination device includes a pressure gauge that detects pressure in a gas storage chamber that stores non-condensable gas generated in an absorber of an absorption refrigerator, and a hydrogen sensor that detects an amount of hydrogen discharged from the gas storage chamber. Further, a determining unit determines a cause of generation of the non-condensable gas stored in the gas storage chamber based on a detection result of the hydrogen sensor and a detection result of the pressure gauge.