Ink jet printing apparatus, dummy jet method, and program

An ink jet printing apparatus comprising:

• an ink jet head that includes nozzles for jetting an ink;
• a dummy jet condition setting unit that sets a non-jettable period as an upper limit of a non-jetting period in which a jettability decrease of the ink jet head does not occur, and a required jetting amount as a lower limit of a jetting amount in the non-jettable period, for each nozzle;
• and
• a dummy jet control unit that executes a dummy jet for a dummy jet execution nozzle with a jetting amount insufficient for the required jetting amount,
• wherein, at a determination timing of determining necessity of execution of a dummy jet, the dummy jet control unit executes a dummy jet in a case where a period from a printing start to a next jetting timing is less than a period obtained by adding a determination interval to a period from the printing start to the determination timing, and does not execute a dummy jet in a case where the period from the printing start to the next jetting timing is equal to or greater than the period obtained by adding the determination interval to the period from the printing start to the determination timing, for the nozzle of which a total jetting amount in the non-jettable period is less than the required jetting amount.