The present invention relates to a flat panel display and an organic light emitting display which maintains an opaque state depending on a user's desired time point or an established time point, while maintaining a transparent state at ordinary times, by forming a transparent two side emission panel and a control unit on the lower portion of the transparent two side emission panel, enabling to freely display an image in two side or one side. A flat panel display (FPD) of the present invention is constructed with a transparent two side emission panel and a control unit provided on at least one side of the transparent two side emission panel to control transmission of light. The control unit controlling an array of liquid crystal layers depending on voltage applied to the liquid crystal layers and transmission of light by a first polarizing member and a second polarizing member. As a result, the present invention maintains an opaque state depending on a user's desired time point or an established time point, while maintaining a transparent state at ordinary times, enabling to freely display an image in two sides or one side.