To provide a furnace-wall structural material preventing so-called reducing corrosion that is corrosion and reductions in thickness due to H2S and COS in combustion gas and a furnace structure comprising the structural material easily at low cost.

This is a furnace-wall structural material with a corrosion- resisting composite coat that is obtained by successively forming an iron oxide layer 2 and a coating layer 3, containing an oxide with the superior affinity with oxygen to the iron oxide layer 2 formed on the surface of a wall surface body 1 comprising steel products. Moreover, a furnace structure comprising the furnace-wall structure provided with the water jacket pipe of a boiler burning sulfur-containing fuel is manufactured by using the furnace-wall structural material with the corrosion-resisting composite coat formed. By heating the wall surface body with oxidizing atmosphere, the iron oxide layer 2 is formed on the surface of the wall surface body, and either aluminum oxide, chromium oxide, silicon oxide, titanium oxide or calcium oxide is used solely or in a compound for the oxide with the superior affinity with oxygen to the iron oxide layer.