To enable a lowering of the concentration of an absorbent at the time of a partial load or the like.

A refrigerant reservoir is formed below a condenser heat exchanger provided for a condenser and a weir 34 partitioning this refrigerant reservoir into a refrigerant liquid storage part 31 and a refrigerant liquid outflow part is provided in the refrigerant reservoir, while a slit 35 in the vertical direction is formed in this weir 34. At the time of a partial load or when the temperature of cooling water is low at the time of the partial load, a refrigerant liquid stored in the refrigerant liquid storage part 31 is made to flow out from the condenser through the opening 35 of the weir 34 and thereby the concentration of an absorbent can be lowered.