To uniformly heat the material to be heated consisting of agglomerated material such as pellet or briquentte in the width direction of a furnace hearth even in the case of adopting the furnace having wide width of the furnace hearth to the furnace height in a movable hearth furnace such as rotary hearth furnace used in the case of reducing metallic oxide such as iron ore.

A separating wall for separating in the furnace in the furnace width direction is continuously or intermittently arranged over the whole length of a heating zone so as to form a space in the interval with the furnace hearth. Thus, the equipment cost is reduced and the productivity is improved and the product small in variation and good in quality is obtained and the energy efficiency is high.