A refrigerating apparatus, comprising: a casing body attached to an opening formed at one end of a box-shaped cooling compartment so as to close the opening; a refrigeration cycle unit including a compressor and a radiator provided on an outer side of the cooling compartment relative to the casing body, and an evaporator provided on an inner side of the cooling compartment relative to the casing body; a diagnosis process executer configured to control the refrigeration cycle unit to execute a diagnosis process for diagnosing a performance of the cooling compartment; and a performance determinator configured to determine the performance of the cooling compartment in the diagnosis process, characterized in that the performance determinator is configured to determine airtightness of the cooling compartment in the diagnosis process, the refrigerating apparatus further comprising: a defrosting end determinator configured to terminate a defrosting operation of the evaporator when an amount of frost on the evaporator falls below a predetermined amount during the defrosting operation, wherein the diagnosis process executer is configured to execute, upon start of the diagnosis process, a cooling operation for cooling an inside of the cooling compartment by the evaporator and then execute the defrosting operation, and the performance determinator is configured to determine the airtightness of the cooling compartment based on a time Δt2 between a point at which the defrosting operation is executed and a point at which the defrosting end determinator terminates the defrosting operation. a casing body attached to an opening formed at one end of a box-shaped cooling compartment so as to close the opening; a refrigeration cycle unit including a compressor and a radiator provided on an outer side of the cooling compartment relative to the casing body, and an evaporator provided on an inner side of the cooling compartment relative to the casing body; a compressor and a radiator provided on an outer side of the cooling compartment relative to the casing body, and an evaporator provided on an inner side of the cooling compartment relative to the casing body; a diagnosis process executer configured to control the refrigeration cycle unit to execute a diagnosis process for diagnosing a performance of the cooling compartment; and a performance determinator configured to determine the performance of the cooling compartment in the diagnosis process, characterized in that the performance determinator is configured to determine airtightness of the cooling compartment in the diagnosis process, the refrigerating apparatus further comprising: a defrosting end determinator configured to terminate a defrosting operation of the evaporator when an amount of frost on the evaporator falls below a predetermined amount during the defrosting operation, wherein the diagnosis process executer is configured to execute, upon start of the diagnosis process, a cooling operation for cooling an inside of the cooling compartment by the evaporator and then execute the defrosting operation, and the performance determinator is configured to determine the airtightness of the cooling compartment based on a time Δt2 between a point at which the defrosting operation is executed and a point at which the defrosting end determinator terminates the defrosting operation. a defrosting end determinator configured to terminate a defrosting operation of the evaporator when an amount of frost on the evaporator falls below a predetermined amount during the defrosting operation, wherein the diagnosis process executer is configured to execute, upon start of the diagnosis process, a cooling operation for cooling an inside of the cooling compartment by the evaporator and then execute the defrosting operation, and the performance determinator is configured to determine the airtightness of the cooling compartment based on a time Δt2 between a point at which the defrosting operation is executed and a point at which the defrosting end determinator terminates the defrosting operation.