To display an image on an electronic paper display properly, even when image data is transmitted continuously from a host of the existing LCD display system, for example. A sampling section inputs a single image data by each prescribed period from a plurality of pieces of continuously transmitted image data corresponding to one screen of the electronic paper display. A difference detecting section detects a difference amount showing a difference between previous image data and latter image data of two pieces of consecutive image data inputted by the sampling section, and determines to perform screen update by using the latter image data when the difference value is equal to or larger than a threshold value. A driving section generates a driving signal of the latter image data and outputs the signal to the electronic paper display, when the screen update is determined by the difference detecting section.