Disclosed is a method of horizontally growing carbon nanotubes, in which the carbon nanotubes can be selectively grown in a horizontal direction at specific locations of a substrate having catalyst formed thereat, so that the method can be usefully utilized in fabricating nano-devices. The method includes the steps of: (a) forming a predetermined catalyst pattern on a first substrate; (b) forming a vertical growth preventing layer on the first substrate, which prevents carbon nanotubes from growing in a vertical direction; (c) forming apertures through the vertical growth preventing layer and the first substrate to expose the catalyst pattern through the apertures; and (d) synthesizing carbon nanotubes at exposed surfaces of the catalyst pattern in order to grow the carbon nanotubes in the horizontal direction.