A display device with dual display areas comprises a transparent substrate, a semi-reflecting layer, a first display area and a second display area. The transparent substrate has a first surface and a second surface, which is opposite to the first surface. The semi-reflecting layer is disposed on the first surface or on the second surface. The first display area comprises, in sequence, a first electrode, at least one first organic functional layer and a second electrode. The first electrode is disposed over the first surface of the transparent substrate. The second display area comprises, in sequence, a third electrode, at least one second organic functional layer and a fourth electrode. The third electrode is disposed over the first surface of the transparent substrate. The thickness of the fourth electrode is larger than the thickness of the second electrode.