To make preset image data arbitrarily changeable.

A display device has an image-data storage section 14 storing a preset first image data, a display section 26 displaying an interface screen by using the first image data and an external storage medium 25 capable of storing a second image data, capable of being displaced with the first image data. The display device further has a control section, storing the second image data read from the external storage medium 25 to an image-data storage section 14, reading the second image data in place of the first image data from the image-data storage section 14, and displaying the interface screen on the display section 26, when the second image data is stored in the external storage medium 25. The interface screen can be changed by the arbitrary second image data.