To provide a display device and its cache control method capable of enhancing speed of a desired image displaying process with respect to a cache area storing an element image after image expansion based upon a compressed image.

The display device preparing and displaying a display image is provided with an expansion buffer storing the element image located in a display buffer by the image expansion of the compressed image corresponding to an image number, and a cache managing means of managing the expansion buffer as the cache area of the element image. Image storage information of the element image is coordinated with cache index information, the cache index information is stored in coordination with the image number, non-storage information is stored instead of the cache index information when the element image is not stored in the cache area, and an existence or nonexistence and a location of each element image in the cache area is searched by searching the non- storage information or each piece of cache index information on the basis of the image number and searching each piece of image storage information on the basis thereof.