A refrigeration device for a container containing a cargo for transportation which comprises a refrigerant circuit including a controller and an evaporator, and which performs low-temperature treatment operation for treating a cargo in an interior of the container under a predetermined low-temperature condition, the refrigeration device comprising: a cargo temperature detector configured to detect a temperature of the cargo, wherein the refrigeration device further comprises: a blow-out temperature detector configured to detect a blow-out temperature of air which is cooled in the evaporator and blown out into the interior of the container; an operation controller configured to perform cooling control of the interior of the container on the basis of the temperature detected by the blow-out temperature detector and the temperature detected by the cargo temperature detector so that the temperature of the cargo satisfies the low-temperature condition in the low-temperature treatment operation; a storage unit configured to store a first set temperature as a control target value for the blow-out temperature in the low-temperature treatment operation and a cargo target temperature as a target value for the temperature of the cargo in the low-temperature treatment operation; and a time measurement unit configured to measure a treatment time elapsed for low-temperature treatment of the cargo in the low-temperature treatment operation, the operation controller being configured to control the refrigerant circuit so that the blow-out temperature approaches the first set temperature upon starting the low-temperature treatment operation, and the time measurement unit being configured to start measuring the treatment time when the temperature of the cargo is lower than the cargo target temperature upon starting the low-temperature treatment operation, wherein in the low-temperature treatment operation, when the predetermined period in which the temperature of the cargo is maintained at the cargo reference temperature or lower is elapsed, the low-temperature treatment operation ends. a cargo temperature detector configured to detect a temperature of the cargo, wherein the refrigeration device further comprises: a blow-out temperature detector configured to detect a blow-out temperature of air which is cooled in the evaporator and blown out into the interior of the container; an operation controller configured to perform cooling control of the interior of the container on the basis of the temperature detected by the blow-out temperature detector and the temperature detected by the cargo temperature detector so that the temperature of the cargo satisfies the low-temperature condition in the low-temperature treatment operation; a storage unit configured to store a first set temperature as a control target value for the blow-out temperature in the low-temperature treatment operation and a cargo target temperature as a target value for the temperature of the cargo in the low-temperature treatment operation; and a time measurement unit configured to measure a treatment time elapsed for low-temperature treatment of the cargo in the low-temperature treatment operation, the operation controller being configured to control the refrigerant circuit so that the blow-out temperature approaches the first set temperature upon starting the low-temperature treatment operation, and the time measurement unit being configured to start measuring the treatment time when the temperature of the cargo is lower than the cargo target temperature upon starting the low-temperature treatment operation, wherein in the low-temperature treatment operation, when the predetermined period in which the temperature of the cargo is maintained at the cargo reference temperature or lower is elapsed, the low-temperature treatment operation ends. a blow-out temperature detector configured to detect a blow-out temperature of air which is cooled in the evaporator and blown out into the interior of the container; an operation controller configured to perform cooling control of the interior of the container on the basis of the temperature detected by the blow-out temperature detector and the temperature detected by the cargo temperature detector so that the temperature of the cargo satisfies the low-temperature condition in the low-temperature treatment operation; a storage unit configured to store a first set temperature as a control target value for the blow-out temperature in the low-temperature treatment operation and a cargo target temperature as a target value for the temperature of the cargo in the low-temperature treatment operation; and a time measurement unit configured to measure a treatment time elapsed for low-temperature treatment of the cargo in the low-temperature treatment operation, the operation controller being configured to control the refrigerant circuit so that the blow-out temperature approaches the first set temperature upon starting the low-temperature treatment operation, and the time measurement unit being configured to start measuring the treatment time when the temperature of the cargo is lower than the cargo target temperature upon starting the low-temperature treatment operation, wherein in the low-temperature treatment operation, when the predetermined period in which the temperature of the cargo is maintained at the cargo reference temperature or lower is elapsed, the low-temperature treatment operation ends.