"However, when the ejection ports are purged of inks in such a state that the recessed portions on the cap cover the nozzle surfaces of the four inkjet heads, there may be caused a case where inks so ejected scatter within the recessed portions to adhere to the nozzle ejection surfaces of the other inkjet heads, whereby the plurality of kinds of inks are mixed with each other at the nozzle surfaces" . . . .