critical time before sucking the black ink is decide at 72 hours and that for color inks is decided at 120 hours through experiments sucking operations for the black ink is sucked by the timer at just the critical threshold timing while sucking operations for color inks are executed by the timer more frequently than required in fig4 b shows sucking schedule according to the present invention where threshold values for black and color inks are set at different values the threshold value tk for executing sucking operation against the black ink is set at 72 hours and the threshold value tc for executing sucking operations against color inks is set at 120 hours based on the results of the experiments compared with the conventional case shown in a of fig4 the frequency of sucking recovery operations against color inks are reduced to 3 5 times of the conventional case while the frequency of sucking recovery operations against the black ink remains at the same frequency as the conventional case thus wasted volume of color inks is suppressed due to frequent sucking operations however an overall frequency of sucking operations during 360 hours is 7 comprising 4 sucking operations against only black ink 2 sucking operations against only color inks and 1 simultaneous sucking operation against black and color inks the sucking operation at the starting point is excluded in this case 7 5 sucking operations are executed compared with 5 simultaneous sucking operations against black and color inks depicted in a of fig 4 sucking recovery operations by the timer are executed when the recording apparatus receives data before printing operations are started consequently the frequent sucking recovery operations make.