There is provided a polymer electroluminescent device, which comprises a transparent substrate, an anode, a polymer emitting layer, a polymer insulating nanolayer and a cathode. The polymer insulating nanolayer having the dielectric constant (.di-elect cons.) of less than 3.0 is located between the cathode and the polymer emitting layer. According to the present invention, it is possible to obtain the polymer electroluminescent device showing more improved luminance efficiency.