Disclosed herein is a method of manufacturing a thin film transistor including titanium oxides as an active layer and the structure of the thin film transistor film manufactured using the method. The thin film transistor includes: a substrate; an active layer formed on the substrate using polycrystalline or amorphous titanium oxides; and an insulating layer formed on the active layer. Further, the method of manufacturing the thin film transistor includes: forming a substrate; forming an active layer on the substrate using polycrystalline or amorphous titanium oxides; and forming an insulating layer on the active layer. The present invention is advantageous in that the performance of the thin film transistor can be improved, the thin film transistor can be manufactured at low cost, harmful environmental problems can be solved, and the thin film transistor can be widely applied to various electronic apparatuses including, but not limited to, integrated drivers in active-matrix displays and transparent electronic devices.