1. A user interface device configured to perform: (a) a display function of displaying an image on a display screen, and (b) a touch panel function of outputting successive locations of the user's finger touch point on a touch screen over time, the user interface device comprising: a screen-pad controller configured to display, while displaying an original image on the display screen, a reference image on the display screen forming a screen pad, the screen pad being defined as an in-screen touch pad, such that the reference image has a reduced size with respect to the original image to partially overlay the reference image with the original image, the original image containing a plurality of user-selectable first objects, the reference image containing a plurality of user-selectable second objects respectively corresponding to at least each of the plurality of first objects; and an operation controller configured to, in response to a user's finger touch with the screen pad, (i) detect one of the plurality of second objects on the screen pad, which has been selected by the user's finger touch, and (ii) recognize the user's input based on one of the plurality of first objects, which corresponds to the selected second object.