A tiled display device is provided. The tiled display device includes a main supporting substrate, a first display substrate and a second display substrate. The first display substrate is disposed on the main supporting substrate. The second display substrate is disposed on the main supporting substrate and adjacent to the first display substrate. In addition, the main supporting substrate includes a light reflection reduction structure. In a top-view direction of the tiled display device, the light reflection reduction structure is overlapped with the gap between the first display substrate and the second display substrate.