An absorption chiller for obtaining a cold water, comprising: a cooling tower, a cooling cycle having a regenerator, a condenser, an evaporator, and an absorber; a cold water pipe configured to supply the cold water received from a cold water inlet to the evaporator, and to supply the cold water cooled by the evaporator from a cold water outlet to an external target device; a cooling water pipe (12a, 14a) that extends from a cooling water inlet to a cooling water outlet via the absorber and the condenser, the cooling water inlet being configured to receive a cooling water from the cooling tower, the cooling water outlet being configured to discharge the cooling water toward the cooling tower; a heating medium pipe configured to supply a heating medium to the regenerator and to discharge the heating medium whose temperature is lowered in response to heating of a dilute solution in the regenerator; a cooling water inlet shut-off valve provided on the cooling water inlet; a cooling water outlet shut-off valve provided on the cooling water outlet; a cooling water temperature detector configured to detect a temperature of the cooling water in the cooling water pipe (12a, 14a); a controller configured to cause the dilute solution in the regenerator to be heated by the heating medium and to cause an obtained concentrated solution to be supplied to the absorber so as to perform a heat exchange with the cooling water in the cooling water pipe (12a, 14a), and to cause a vapor refrigerant generated by the heating of the dilute solution to perform the heat exchange with the cooling water of the cooling water pipe (12a, 14a) in the condenser, when the temperature detected by the cooling water temperature detector is equal to or lower than a predetermined temperature, in a wet lay-up state including a state in which the cooling water inlet shut-off valve and the cooling water outlet shut-off valve are closed and the cooling water pipe (12a, 14a) is filled with the cooling water; and a first pressure relief valve provided on the cooling water pipe (12a, 14a), wherein the controller is further configured to control the pressure relief valve to relieve an internal pressure in the cooling water pipe (12a, 14a) generated from the heat exchange. a cooling tower, a cooling cycle having a regenerator, a condenser, an evaporator, and an absorber; a cold water pipe configured to supply the cold water received from a cold water inlet to the evaporator, and to supply the cold water cooled by the evaporator from a cold water outlet to an external target device; a cooling water pipe (12a, 14a) that extends from a cooling water inlet to a cooling water outlet via the absorber and the condenser, the cooling water inlet being configured to receive a cooling water from the cooling tower, the cooling water outlet being configured to discharge the cooling water toward the cooling tower; a heating medium pipe configured to supply a heating medium to the regenerator and to discharge the heating medium whose temperature is lowered in response to heating of a dilute solution in the regenerator; a cooling water inlet shut-off valve provided on the cooling water inlet; a cooling water outlet shut-off valve provided on the cooling water outlet; a cooling water temperature detector configured to detect a temperature of the cooling water in the cooling water pipe (12a, 14a); a controller configured to cause the dilute solution in the regenerator to be heated by the heating medium and to cause an obtained concentrated solution to be supplied to the absorber so as to perform a heat exchange with the cooling water in the cooling water pipe (12a, 14a), and to cause a vapor refrigerant generated by the heating of the dilute solution to perform the heat exchange with the cooling water of the cooling water pipe (12a, 14a) in the condenser, when the temperature detected by the cooling water temperature detector is equal to or lower than a predetermined temperature, in a wet lay-up state including a state in which the cooling water inlet shut-off valve and the cooling water outlet shut-off valve are closed and the cooling water pipe (12a, 14a) is filled with the cooling water; and a first pressure relief valve provided on the cooling water pipe (12a, 14a), wherein the controller is further configured to control the pressure relief valve to relieve an internal pressure in the cooling water pipe (12a, 14a) generated from the heat exchange.