When growing carbon nanotubes, a substrate is delivered into a thermal CVD chamber whose internal temperature is a room temperature, and a mixed gas of an inert gas and a raw gas is introduced in the inside thereof. After a pressure inside of the chamber is stabilized at 1 kPa, the temperature in the chamber is raised to 510° C. in 1 minute. As a result, the carbon nanotubes start to grow linearly from the respective catalytic particles without any fusion of each of the catalytic particles. Subsequently, the temperature and an atmosphere are maintained for about 30 minutes. Once the carbon nanotubes start to grow, surfaces of the catalytic particles are covered by carbon, so that any fusion of each of the catalytic particles can be avoided even during the maintenance for about 30 minutes.