The present invention improves luminance and light emitting efficiency of electroluminescent elements. A manufacturing method of electroluminescent elements includes forming a positive electrode on a substrate, forming an organic compound layer on the positive electrode, forming an electron injecting layer on the organic compound layer, and forming a transparent conductive film on the electron injecting layer, thus forming electroluminescent element. After forming the transparent conductive film on the electron injecting layer, by applying a voltage between the positive electrode and the transparent conductive film while heating the electroluminescent element, light emission of the electroluminescent element such as luminance and light emitting efficiency is improved.