Carbon nanotubes, with their unique structure, are expected to have a variety of applications as industrial materials. However, carbon nanotubes synthesized using the laser ablation method or are discharge evaporation method always include other carbonaceous materials. Purification is a very important step in the use of carbon nanotubes as industrial materials. For the efficient recovery of nanotubes it is very important to clarify the gasification behaviour of the nanotube-containing material during the purification step. In this study, the gasification behaviour of a nanotube-containing material with various gasification agents was investigated in detail using a fixed-point observation technique and scanning electron microscopy. The gasification manner of the carbon nanotube-containing material was clarified using oxygen, carbon dioxide and hydrogen plasma as the gasifying agents. The gasification behaviour of the sample depended on the kind of reactant gas. In hydrogen plasma, carbon nanotubes were partly purified. Under the experimental conditions examined, oxygen gasification at 1023 K was the most effective method for purification of carbon nanotubes, and nanotubes were recovered selectively.