In a rotary hearth furnace for producing reduced metal through heating and reducing carbon containing materials composed of at least metal oxide-containing material and carbon-containing reduction material, a hearth structure is provided by which a refractory in a hearth lateral end is not damaged and carbon containing materials do not fall down to a water sealing section of the rotary hearth furnace. The upper part of a hearth lateral end 1a is covered with the lower end 2a of a side wall 2 of a hood covering the whole hearth, and a cooling means 3 is installed in the side wall lower end 2a.