To provide a method which has excellent productivity and little heat loss, related to a heating method in a continuous charging type heating furnace.

A steel slab 1 is carried from a charging hole 2 toward an ejecting hole 3 in the heating furnace. At the ejecting hole 3 side of the heating furnace, a heating zone 4 provided with plural air/fuel burners 41 (may be used to an oxygen dope type). At the charging side 2, a flue gas recuperation zone 5 is arranged and the flue gas is exhausted through there. At least one of bulky fuel in the gas state is injected into the flue gas. Oxygen is introduced into further upstream side than the air/fuel gas burner 41 disposed at the uppermost stream side in the carrying direction of the steel slab 1. In this way, the bulky fuel in the gas state is burnt to raise the temp. of the recuperation zone 5. The method can be applied to the heating of the steel slab before rolling in an iron-making process.