A stacked display device and a control method thereof are provided. The stacked display device includes a stacked display including a first panel and a second panel comprising a different transmittance from the first panel and a processor to obtain a first layer image to display an image on the first panel and a second layer image to display an image on the second panel, adjust brightness of the second layer image based on a ratio between a first transmittance for the first panel and a second transmittance for the second panel, and a pixel value of the second layer image, and control the stacked display to display the second layer image of which brightness is adjusted on the second panel while displaying the first layer image on the first panel.