To greatly increase output by recovering the power of high temperature combustion gas for waste power generation by a gas turbine cycle, and composing a compound power generating system in a manner that power is recovered from gas turbine exhaust and low temperature combustion gas by a Kalina cycle.

High temperature/high pressure gas after discharged from a compressor 4, and heated by a heat exchanger 6 arranged in a high temperature corrosive exhaust gas source 1 from a waste incinerator or the like, is worked by being supplied to a sealed gas turbine 2. Gas discharged from the gas turbine 2 is returned to the compressor 4 after its heat is recovered through first to third heat exchangers 7, 9 and 12. Further, an ammonia-water mixture fluid steam turbine 3 is driven by the steam of a Kalina cycle, which is heated by a heat exchanger 10 arranged in the exhaust gas source 1 so as to operate a generator 13. After that, steam of which work has finished is sent to the heat exchanger 9 after being condensed by a distillation condensing system 8, and returned to the heat exchanger 10 after steam temperature is raised by high temperature gas discharged from the gas turbine 2.