The present invention provides: a tubular body used in high temperature atmospheres; and a method for stably forming a metal oxide layer to have a high surface area on the inner surface of the tubular body. This tubular body used in high temperature atmospheres is made of a heat resistant alloy, which contains 15% or more of Cr and 18% or more of Ni in mass%, and has the inner surface of which the arithmetic average roughness (Sa) of the three-dimensional surface roughness satisfies 1.5≤Sa≤5.0, and the skewness (Ssk) of the surface height distribution satisfies |Ssk|≤0.30. Said heat resistant alloy may contain 2.0% or more of Al in mass%. The kurtosis (Sku) of the surface height distribution of the three-dimensional surface roughness of the inner surface may satisfy Sku≥2.5.
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