A flexible display device is provided. The flexible display device includes a display extendable from the device; a sensor to detect an extended amount of the display; and a controller configured to cause the display to display a home screen on a pre-extension display region, which is a region of the display that is visible prior to extending of the display; cause the display to display a folder including an application icon corresponding to an application, wherein the folder and the application icon are displayed on the pre-extension display region; detect, via the sensor, extension of the display; and cause the display to display the folder enlarged and the application icon enlarged on an extended display region, which is a region of the display that is visible after extending of the display.