A method for forming a silicon carbide-natured refractory block comprising: a molding process, including pouring a silicon carbide-natured refractory castable, which includes Al 2 O 3, SiO 2 and SiC in a chemical constituent ratio of 3% by mass, 4% by mass and 86% by mass, respectively, into a mold having a predetermined configuration, and making a molded block with a predetermined configuration by drying at 110°C for 24 hours; and an oxidized calcination process making a sintered block by heating the molded block, including heating an outer superficial portion of the molded block at 1400°C or more in air being an oxygen environment, thereby oxidizing at least some of the silicon carbide on the outer superficial portion of the molded block, thereby turning the silicon carbide into silicon oxide, and thereby forming an oxidized calcination coated layer having a thickness of 1 mm; wherein the silicon carbide-natured refractory includes silicon carbide in an amount of 50% by mass or more when the entirety is taken as 100% by mass; and wherein the silicon carbide-natured refractory block comprises a fire-resistant block body and the calcination coated layer, and wherein the components of the fire-resistant block body other than silicon carbide include oxides of silicon, oxides of aluminum, oxides of calcium, carbides of aluminum, carbides of calcium and/or a metal. a molding process, including pouring a silicon carbide-natured refractory castable, which includes Al 2 O 3, SiO 2 and SiC in a chemical constituent ratio of 3% by mass, 4% by mass and 86% by mass, respectively, into a mold having a predetermined configuration, and making a molded block with a predetermined configuration by drying at 110°C for 24 hours; and pouring a silicon carbide-natured refractory castable, which includes Al 2 O 3, SiO 2 and SiC in a chemical constituent ratio of 3% by mass, 4% by mass and 86% by mass, respectively, into a mold having a predetermined configuration, and making a molded block with a predetermined configuration by drying at 110°C for 24 hours; and an oxidized calcination process making a sintered block by heating the molded block, including heating an outer superficial portion of the molded block at 1400°C or more in air being an oxygen environment, thereby oxidizing at least some of the silicon carbide on the outer superficial portion of the molded block, thereby turning the silicon carbide into silicon oxide, and thereby forming an oxidized calcination coated layer having a thickness of 1 mm; heating an outer superficial portion of the molded block at 1400°C or more in air being an oxygen environment, thereby oxidizing at least some of the silicon carbide on the outer superficial portion of the molded block, thereby turning the silicon carbide into silicon oxide, and thereby forming an oxidized calcination coated layer having a thickness of 1 mm; the silicon carbide-natured refractory block comprises a fire-resistant block body and the calcination coated layer, and wherein the components of the fire-resistant block body other than silicon carbide include oxides of silicon, oxides of aluminum, oxides of calcium, carbides of aluminum, carbides of calcium and/or a metal.