A UI device of a digital camera has a display screen, a left-side touch strip provided outside of and on a left side of the display screen and a right-side touch strip provided outside of and on a right side of the display screen. The touch strips 22 and 24 can distinguishably detect a slide operation in a vertical direction by the user and a slide operation in a horizontal direction by the user. When a slide operation in the vertical direction is detected, a controller of the UI device recognizes the operation as a manipulative instruction in which the amount of movement is considered important, such as an operation for selection of items or scrolling of a screen. When a slide operation in the horizontal direction is detected, the controller recognizes the slide operation as a triggering manipulative instruction in which the amount of movement is not as important, such as a file deletion instruction or display or non-display of a new hierarchical item.