PURPOSE: To provide ultra-fine tube excellent in the chemical resistance and its manufacturing method by forming the anodically oxydized film on the surface of a rod-shaped body, and removing the part which is not anodically oxydized of this processed rod-shaped body.

CONSTITUTION: An aluminum rod-shaped body 1 is formed, the anodic oxidation of the surface is executed to form a processed rod-shaped body 3 where the anodically oxydized film 2 is formed. After the processed rod-shaped body 3 is cut to the prescribed length, it is dipped in hydrochlolic acid to remove the rod-shaped body 1a which is not anodically oxydized. Then, the adhered hydrochlolic acid is removed by dipping the rod-shaped body in running water to form an ultra-fine tube 4 of anodic oxidation film 2. This ultra-fine tube 4 is left in hydrochlolic acid, sulfuric acid, nitric acid or the like to check the acid resistance, left in sodium hydroxide solution or the like to check the alkali resistance, and left in the atmosphere of the gaseous chloride or the like to check the corrosive gas resistance, and the chemical resistance is found excellent in all cases. This constitution realizes the ultra-fine tube and its manufacturing method excellent in the chemical resistance where the inner diameter is the prescribed value or under.