There is provided a thin film forming apparatus for precisely forming a film of an organic EL material made of a polymer without a positional deviation and at a high throughput. A pixel portion is divided into a plurality of pixel lines by banks, and a head portion of the thin film forming apparatus is moved along the pixel lines, so that a coating liquid (R), a coating liquid (G), and a coating liquid (B) can be applied respectively in a stripe shape at the same time. Then, luminescent layers emitting lights of respective colors of red, green and blue can be formed by heating these coating liquids.