A display unit which can detect the X coordinate of a position with which a pen is in contact more efficiently. In a non-display period, X-electrodes are grouped into N regions according to the X-electrode arrangement, each region is divided into two parts according to the X-electrode arrangement, and selection voltage is applied to the X-electrodes belonging to each part having larger X coordinates. The process is repeated in order while N is doubled from one to the half value of the number of the X-electrodes of a liquid crystal panel. If a pen coming in contact with the liquid crystal panel and detecting X-electrode selection voltage detects selection voltage with respect to each N value, the Nth most significant bit of the X coordinate of the position with which the pen is in contact is set to `1.` If the pen does not detect selection voltage, the bit is set to `0.` Thus, the X-electrode of the position with which the pen is in contact can be detected at the number of selection voltage application times equal to the minimum number of bits that can represent each of the X-electrodes.