Ink circulation type inkjet printer

An ink circulation type inkjet printer comprising:

• a plurality of inkjet heads, each of which provided with multiple nozzles to eject ink;
• a plurality of ink circulation routes, which include the plurality of inkjet heads, respectively;
• a maintenance mechanism that executes maintenance processing for the plurality of inkjet heads;
• an ink circulation controller configured to circulate ink in all of the plurality of ink circulation routes for each printing job;
• and
• a maintenance controller configured to:
• (1) allow the maintenance mechanism to execute the maintenance processing for the plurality of inkjet heads before a present printing job under three conditions that:
• (c1) an elapsed time from a last printing job to the present printing job is less than a first reference time;
• (c2) the present printing job requests for ejecting ink from unused nozzles of the multiple nozzles in the last printing job;
• (c3) the elapsed time is more than a second reference time;
• (2) allow the ink circulation type inkjet printer to perform the present printing job without the maintenance processing for the plurality of inkjet heads when the elapsed time is less than the predetermined second reference time.