To ensure safety operation at high energy efficiency while suppressing contamination by providing a single number of chamber with a top section having a cold scrap inserting means, a bottom section having means for discharging heated scrap, and a gate means through which gas permeates from the top section to the bottom section.

A scrap preheater 1 comprises a main vertical preheating chamber 3, an automatic charger assembly 72 for elevating an inclining scrap box 37, and a charge mechanism 57 for transporting an iron scrap mixture 8/3. The chamber 3 is divided by two sets of iron grids 4/1, 5/1 for controlling lowering of scrap into three sections, i.e., a top section 5, an intermediate section 6 and a bottom section 7. Each section is introduced into the preheater 1 on order to control gradual temperature increase of the iron scrap mixture 8/3 descending gravitationally thus ensuring safety operation at high energy efficiency while suppressing contamination.