A layer included in an electroluminescent element is required to be thickened to optimize light extraction efficiency of the electroluminescent element and to prevent short-circuit between electrodes. However, in a conventional element material, desired light extraction efficiency cannot be accomplished since drive voltage rises or power consumption is increased as the element material is thickened. A composite is formed by mixing a conjugated molecule having low ionization potential and a substance having an electron-accepting property to the conjugated molecule. A composite layer included in an element is formed using the composite as an element material. The composite layer is arranged between a first electrode and a light emitting layer or between a second electrode and a light emitting layer. The composite layer has high conductivity; therefore, drive voltage does not rise even if a film thickness is increased. Thus, an electroluminescent element which can prevent short-circuit of an electrode can be provided.