To provide an exhaust heat recover heat-exchanger to ensure a stable flow of drum water circulating between the steam drum and the vaporizer of a steam generating part during starting operation.

In an exhaust heat recovery heat-exchanger having a vaporizer 74 communicated with a steam drum 73, steam is fed to drum water circulating from the steam drum 73 through the vaporizer 74, and a steam feed pipe 86 to increase a circulation force in a way to produce a two-phase flow is arranged at a vaporizer 74. Before combustion gas is fed to the vaporizer 74, drum water is circulated from a steam drum 73 through a vaporizer 74. In a starting operation method, described above, of the exhaust heat recovery heat-exchanger, steam to increase a circulation force by bringing drum water, circulating from the steam drum 73 through the vaporizer 74, into a two-phase flow is fed. After combustion gas is fed to the vaporizer 74, a regulation valve for a steam feed pipe 86 through which steam is fed to circulating water is closed after combustion gas is fed to the vaporizer 74.