<p>PURPOSE: A display device is provided to control transmittance of external light with low power by arranging optical devices in a transparent display device. CONSTITUTION: A transparent display device(10) includes a first region and a second region. The first region emits light to one side. The second region is located near the first region and transmits external light. A first polarization plate(21) transmits the external light by linear polarization. A first retarder(41) transmits the external light by delaying the phase of the external light. [Reference numerals] (AA) Image</p>
