An image displaying device with an image cache data storage unit, including: an image cache identifier generating unit that obtains a hash value of a fixed length from sampling data of original image data and generates an image cache identifier unique to said original image data based on the hash value of a fixed length; an image cache searching unit that checks whether image cache data to which the generated image cache identifier is added is stored in said image cache memory or not; and an image cache generating unit that, when the image cache data has been not stored in said image cache memory, generates image cache data by adding the image cache identifier generated by said image cache identifier generating unit to the original image data and stores the image cache data in said image cache memory.