The present application relates to an organic thin film transistor with tunneling barrier layer and method of manufacturing the same improving the mobility properties of the thin film transistor and preventing the current crowding at low voltages. The organic thin film transistor includes a buffer layer on a substrate, a source and drain electrodes on the buffer layer, wherein each of the source and drain electrodes is in an island shape, a tunneling barrier layer on the source and drain electrodes, an organic semiconductor layer on the tunneling barrier layer, a gate insulation layer on the organic semiconductor layer, and a gate electrode overlapping both edges of the source and drain electrodes, and formed on the gate insulation layer, and wherein the tunneling barrier layer under the organic semiconductor layer is formed between the source and drain electrodes and the gate electrode.