Abstract: This invention provides a method capable of fabricating, by simple manufacturing processes, a color conversion layer which realizes high-efficiency color conversion characteristics without greatly increasing the film thickness of the color conversion layer. Further, this invention provides a color conversion layer manufactured by this method, and an organic EL element which includes this color conversion layer. By means of a method in which a polymer material having a weight-average molecular weight in a specific range is brought into contact with a color conversion material layer, and the polymer material is caused to intrude into the color conversion layer by a diffusion phenomenon, concentration quenching in the color conversion layer can be suppressed, and the fluorescence quantum yield can be increased.