Disclosed is a transparent display device for enhancing image quality, and the transparent display device may include liquid crystal display panel; a light source disposed at one side of a lower portion of the liquid crystal display panel to emit light; a first polarizing plate to first-polarize the light emitted from the light source; a light guide plate at a lower portion of the liquid crystal display panel to receive the light first-polarized by the first polarizing plate through a lateral surface thereof, a pattern being formed on the upper surface of the light guide plate to output the incident first-polarized light in a lower direction of the light guide plate; a second polarizing plate at an upper portion of the liquid crystal display panel to control the amount of light transmitting the liquid crystal display panel; and a first optical sheet at a lower portion of the light guide plate to reflect the first-polarized light received from the light guide plate, and transmit a second polarization component of natural light received from the lower portion thereof.