To provide a heat source plant contributive to stable operation of the load of each heat exchanger by supplying heat source water stably to a plurality of heat exchangers.

An absorption refrigerating machine 1 and a hot water heat exchanger 2 are disposed, in series along a heat source water supply pipe line 3 and a heat source water return pipe line 4, so that heat source water is supplied sequentially to the absorption refrigerating machine 1 and the hot water heat exchanger 2 from an heat source. The heat source water supply pipe line 3 and the heat source water return pipe line 4 are coupled with three-way valves 21, 25 so that the heat source water supplied to the absorption refrigerating machine 1 and the hot water heat exchanger 2 can be bypassed.