Abstract: The purpose of the present invention is to provide a method for producing boron nitride nanotubes, said method reducing the ratio of by-products having less reinforcing effects such as boron nitride fullerenes and boron nitride thin pieces, while enhancing the yield at the same time, without requiring a thermal oxidation treatment. The present invention provides a method for producing boron nitride nanotubes, said method being characterized by comprising: a step for obtaining a suspension by mixing a starting material that contains boron nitride nanotubes, a nonionic polymer dispersant having an sp3-bonded CH group, and an organic solvent; and a step for obtaining a dispersion liquid containing boron nitride nanotubes by subjecting the thus-obtained suspension to centrifugal separation, thereby removing by-products contained in the starting material.