By subjecting a starting material composition containing hexafluorobutadiene and at least one additional compound selected from the group consisting of octafluoro-1-butene, octafluoro-2-butene, heptafluoro-1-butene, and heptafluoro-2-butene to extractive distillation in the presence of an extraction solvent to reduce the concentration of the additional compound, hexafluorobutadiene with higher purity can be obtained.