An organic thin field transistor is disclosed. The organic thin field transistor includes a first and a second insulting layers, a metal structure and an organic layer serving as an active layer. Materials of the first and the second insulting layers are different, and by performing an etching process, a surface of the metal structure and a surface of the second insulting layer are effectively aligned. Because of the high flatness of the surface of the metal structure and the second insulting layer, a continuous film-forming property and crystallinity of the active layer of the organic thin field transistor are improved, so as to achieve a better the electrical characteristic.