A method and device for increasing a resolution for each viewpoint in a glassless three-dimensional (3D) display. A method of controlling a three-dimensional (3D) display device including a display panel and a lens includes performing time-division on a plurality of viewpoint images such that each of the viewpoint images is divided into n division images, transferring the division images to the display panel by increasing n times a frame rate of the division images, and controlling the lens such that the division images transferred to the display panel pass through a lens cell.