A method of manufacturing a thin film transistor includes forming a gate electrode, forming a gate insulating layer on the gate electrode, forming an organic semiconductor layer on the gate insulating layer, forming a solvent selective photosensitive layer on the organic semiconductor layer, forming an organic semiconductor pattern and a solvent selective photosensitive pattern by simultaneously patterning the organic semiconductor layer and the solvent selective photosensitive layer, respectively, and forming a source electrode and a drain electrode on the organic semiconductor pattern and the solvent selective photosensitive pattern, the source electrode and the drain electrode being electrically connected to the organic semiconductor pattern.