Disclosed herein is a submount to mount a light emitting diode in a flipchip-structured light emitting device. The submount including a transistor to mount a nitride semiconductor light emitting diode in a flipchip-structured light emitting device includes: a substrate made of a first conductive semiconductor material; a first region formed on a partial area of the substrate, and made of a second conductive semiconductor material; a second region formed on the remaining regions other than the first region, and made of the second conductive semiconductor material; first and second electrodes formed on the first and second regions, respectively; and a conductive layer formed on the back of the substrate, wherein the first and second electrodes are connected to an n-type electrode and a p-type electrode of the nitride semiconductor light emitting diode through the use of a bump.