In a steam-heating apparatus in which a heating section (2) formed in a heat exchanger (1) is connected to a steam supply pipe (3) for receiving supply of heating steam and connected also to a condensate recovering unit apparatus includes a steam ejector (5) including a suction chamber (13) connected to the heating section (2) and an inlet for receiving supply of the steam. The apparatus comprising a condensate tank (11) disposed between the heating section (2) and the condensate recovering unit (6). When the temperature of the heating section (2) or between the heating section (2) and the condensate recovering unit (6) is dropped by a predetermined value, steam is supplied from the steam supply pipe (3) to the inlet of the steam ejector (5) and gas in the heating section (2) is sucked into the suction chamber (13) of the steam ejector (5).