Abstract: The present invention relates to an intracellular expression enhancing genetic element, which enhances the intracellular expression of target protein encoded in RNA therapeutics such as mRNA vaccines and RNA medicines. In more detail, the present invention relates to the RNA molecule which has the genetic element capable of enhancing the intracellular expression of target protein encoded in RNA therapeutics delivered into cells; the plasmid used to synthesize the RNA molecule having the genetic element “E3”; the method for synthesizing RNA molecule having the genetic element “E3” using the plasmid and utilizing the synthesized RNA molecule as RNA therapeutics.