To provide a double-chamber furnace and a steel product heating method capable of improving combustion efficiency of a steel product, and further improving a fuel efficiency and working efficiency of a heating means.

In this double-chamber furnace 1, a steel product 19 carried in a heating chamber 3 is heated by a burner 5, and the air in the heating chamber 3 enters into a heating chamber 4 from a through hole 2b of a partitioning wall 2a to preheat a steel product 20 carried in the heating chamber 4. Then the air in the heating chamber 4 is introduced to a recuperator 8 through an exhaust pipe 10, and exchanges the heat with the air introduced from an outside air introduction pipe 16. The air is sent to the burner 5 of the heating chamber 3 from the recuperator 8 through an air supply pipe 18, and used as the combustion air of the burner 5. Then the steel product 20 is heated in the heating chamber 4, and the next steel product 19 is preheated in the heating chamber 3.