PURPOSE: To prevent an abnormal stop of an absorption refrigerating machine for achieving the stability in operation by providing such a function that the refrigerant is sent from an evaporator to an absorber according to a signal from a comparison- judgement device which receives signals from physical quantity detectors, compares them with set values and outputs a signal.

CONSTITUTION: Detectors 34, 35 and 36 detect such physical quantities as the regeneration temperature and pressure of a high temperature regenerator 1 on the refrigerant condensing temperature of a condenser 3 which vary due to incursion of no-condensing gases and fouling of cooling water. When the temperatures, etc., detected by the detectors increase and a comparison-judgement device 33 receives those detected signals, compares them with set values and outputs a signal, the refrigerant is sent from an evaporator 4 to an absorber 5. Then, the absorption of the refrigerant vapor in the absorber is halted because the absorber 5 is diluted with the refrigerant, and the temperature of cooling water to be sent to a condenser 3 is lowered, so that the refrigerant condensing temperature in the condenser 3 drops, causing the regeneration temperature and pressure in a high temperature regenerator 1 to fall. As a result, an abnormal stop of an absorption refrigerating machine due to a sharp rise in the regeneration temperature is avoided, allowing the absorption refrigerating machine to operate stably.