Abstract: A mode-selecting apparatus for selecting one of a first mode in which images are displayed on a display unit in accordance with a vertical synchronization control signal and a horizontal synchronization control signal, and a second mode in which images are displayed on the display unit in accordance with a data-enable signal, includes a first unit which counts a number of input horizontal synchronization control signals in each of frame periods, a second unit which counts a number of input data-enable signals in each of frame periods, and a third unit which selects one of the first and second modes in accordance with both the number of input horizontal synchronization control signals and the number of input data-enable signals.