In a method of forming a conductive line for a semiconductor device using a carbon nanotube and a semiconductor device manufactured using the method, the method includes activating a surface of an electrode of the semiconductor device using surface pretreatment to create an activated surface of the electrode, forming an insulating layer on the activated surface of the electrode, and forming a contact hole through the insulating layer to expose a portion of the activated surface of the electrode, and supplying a carbon-containing gas onto the activated surface of the electrode through the contact hole to grow a carbon nanotube, which forms the conductive line, on the activated surface of the electrode. Alternatively, the activation step of the surface of the electrode may be replaced with a formation of a catalytic metal layer on the surface of the electrode.