In an ink-jet printing apparatus which includes a plurality of printing heads (IJH) each having an array of ink discharging elements, preliminary discharge of driving the elements of at least one printing head is performed a predetermined number of times as a unit in performing preliminary discharge of discharging ink irrelevant to printing. The printing head for which the preliminary discharge is to be performed is switched to other at least one printing head in a predetermined cycle (T 11 ). In performing the preliminary discharge and switching of the printing head are so controlled as to perform preliminary discharge a desired number of times for all the elements of the printing heads by repeating the cycle.