Provided are a thin film transistor (TFT) and a method of manufacturing the TFT. The TFT includes a substrate; a first conductive type semiconductor layer on the substrate and having a recess; second conductive type spacers at opposite side walls in the recess; a main semiconductor layer covering the first conductive type semiconductor layer and the second conductive type spacers and comprising a channel region and source and drain regions; a gate insulating layer on the main semiconductor layer; and a gate electrode on the gate insulating layer and corresponding to the recess.