A stereoscopic image display device that enables 2D/3D image output conversion includes a display panel configured to display an image and a polarization lens panel disposed on the display panel and configured to transmit as-is or refract light supplied from the display panel according to an image display mode. The polarization lens panel includes: first and second substrates; a lower electrode formed on the first substrate; an upper electrode formed on the second substrate; and a polymer liquid crystal layer formed of a polymer liquid crystal in which a polymer and a liquid crystal are combined, and disposed between the lower electrode and the upper electrode.