A display device includes a signal receiver connecting with one among a plurality of source devices, and configured to receive a content signal from the connected source device. A display is configured to display an image based on a content signal received through the signal receiver. A processor is configured to acquire time information corresponding to a time from a point of connecting with the source device to a point of displaying an image when the source device is connected to the signal receiver, and to control the display to display a user interface (UI) to indicate a connected state based on the acquired time information.