An electrochromic display device (ECD) for an optical pick-up apparatus which is capable of maximizing a transmissivity of a laser beam by forming a reflection prevention layer on the outer surfaces of transparent substrates, includes first and second transparent substrates formed at both sides of the ECD with a predetermined interval therebetween, first and second transparent electrodes coated on the inner surfaces of the transparent substrates, respectively, an electrochromic layer coated on the inner surface of the second transparent electrode so that colorizing or decolorizing may be carried out reversibly, a counter eletrode layer coated on the inner surface of the first transparent electrode, an electrolytic layer formed between the counter electrode layer and the electrochromic layer, and a reflection prevention layer coated to have more than one layer so as to prevent a beam from being reflected on the outer surfaces of the first and second transparent substrates.