The effect of hydrogen and oxygen plasma treatments on the structural properties of carbon nanotube(CNT) has been systematically investigated. As the plasma power was increased, nano particles were appeared at the surface of CNTs. At high plasma power(300 Watt), the structure of CNT was changed from nanotube type to nano particles. However, in case of hydrogen plasma treatment, there was no change in microstructure of CNT. From the Raman analysis, the crystallinity of CNT was deteriorated by the plasma treatment, regardless of gas types.