To recover a corrosion product captured by a filter for a corrosion product even during operation of an absorption water cooler-heater.

The device includes an outflow pipe passage 11 extended from an absorbing liquid circulation passage 2 of the absorption water cooler-heater 1, a first absorbing liquid tank 13 connected to the outflow pipe passage 11, a first valve 12 opening and closing the outflow pipe passage 11, an inflow pipe passage 15 extended from the first absorbing liquid tank 13 and connected to the absorbing liquid circulation passage 2, a second valve 16 opening and closing the inflow pipe passage 15, the filter 14 for the corrosion product interposed between the outflow pipe passage 11 and the inflow pipe passage 15 in the first absorbing liquid tank 13 and capable of being excited, a recovery pipe passage 20 extended from a corrosion product receiving part 13a positioned in a lower part of the filter 14 for the corrosion product, a second absorbing liquid tank 30 detachably connected to the recovery pipe passage 20, a recovery valve 21 opening and closing the recovery pipe passage 20, and an evacuation means 40 provided on the second absorbing liquid tank 30 and maintaining the vacuum state between the first absorbing liquid tank 13 and the second absorbing liquid tank 30.