The present invention relates to a nano-scale light-emitting diode (LED) element for a horizontal array assembly, a manufacturing method thereof, and a horizontal array assembly including the same, and more particularly, to a nano-scale LED element for a horizontal array assembly that can significantly increase the number of nano-scale LED elements connected to an electrode line, facilitate an arrangement of the elements, and implement a horizontal array assembly having a very good electric connection between an electrode and an element and a significant high quantity of light when a horizontal array assembly having the nano-scale LED elements laid in a length direction thereof and connected to the electrode line is manufactured, a manufacturing method thereof, and a horizontal array assembly including the same.