PURPOSE: To detect clogging state of a filter of a condenser in a vending machine and accurately inform the time of cleaning.

CONSTITUTION: A sensor 31 detects the temperatures of the outside air sucked into a refrigerating chamber 1, and a sensor 32 detects the temperatures of a condenser 3. The signals from the sensors 31 and 32 are processed by a microcomputer 41 and the clogging state of a filter 10 of the condenser 3 can be relatively easily judged from differences between both the temperatures, changes in the temperature differences with time and others. As a result, maintenance and management of a vending machine can be easily performed.