A method of vertically aligning pure carbon nanotubes on a large glass or silicon substrate at a low temperature using a low pressure DC thermal chemical vapor deposition method is provided. In this method, catalytic decomposition with respect to hydro-carbon gases is performed in two steps. Basically, an existing thermal chemical vapor deposition method using hydro-carbon gases such as acetylene, ethylene, methane or propane is used. To be more specific, the hydro-carbon gases are primarily decomposed at a low temperature of 400-500.degree. C. by passing the hydro-carbon gases through a mesh-structure catalyst which is made of Ni, Fe, Co, Y, Pd, Pt, Au or an alloy of two or more of these materials. Secondly, the catalytically- and thermally-decomposed hydro-carbon gases pass through the space between a carbon nanotube growing substrate and an electrode substrate made of Ni, Fe, Co, Y, Pd, Pt, Au or an alloy of two or more of these materials or an electrode substrate on which Ni, Fe, Co, Y, Pd, Pt, Au or an alloy of two or more of these materials is thinly deposited by sputtering or electron-beam evaporation, the space to which DC voltage has been applied.