To provide an improved mechanism for unclogging the nozzles in the print head of an ink jet printer without requiring a significant amount of extra cost and providing a better ink supply performance of print head.

The ink jet printer comprises a piezoelectric print head arranged to eject ink upon application of a voltage pulse to a piezoelectric element 12. A print signal generator 44 generates a first magnitude print voltage pulse being applied to the piezoelectric element 12 in order to eject a print ink drop from the print head, and a second magnitude unclogging voltage pulse larger than the first magnitude for unclogging the print head. A controller 16 applies the print voltage pulse or the unclogging voltage pulse selectively to the print head.