To efficiently diagnose or predict a trouble of a showcase or a refrigerator.

A controller 30 calculates three items of a change amount (pressure change amount) of each day of a pressure at a discharge side of the refrigerator 5, a change amount (lowering time change amount) of each day of a time (lowering time) required to lower a temperature of a cold air to a predetermined temperature and a change amount (time difference change amount) of each day of a difference (time difference) of a time required to lower an indoor temperature to a predetermined temperature and a lowering time based on detected results of sensors 18, 20 and 22. In the case of judging a trouble, a ratio of a value of each item obtained at the day to a value (reference value) of each item obtained at an initial time of starting operating is calculated. The magnitude of the ratio is judged. A cause of the trouble regarding the largest item is transmitted to an alarm 35.