Disclosed is a control method of a display device including displaying a playback screen of video images, the playback screen of the video images showing one video image and a progress bar to visualize the progression of the video images, acquiring time information regarding respective bookmark images associated with the video images, the bookmark images respectively including the time information in the sequence of the video images and/or frame information regarding one video image corresponding to the time information, and displaying the bookmark images close to the progress bar at positions corresponding to the time information regarding the respective bookmark images. When a difference between first time information regarding a first bookmark image and second time information regarding a second bookmark image is a time threshold or less, the first and second bookmark images among the bookmark images are displayed as overlapping each other.