To provide a method for setting a driving voltage of an inkjet head whereby whether or not the driving voltage for obtaining a predetermined jet velocity by the inkjet head is appropriate can be distinguished.

After a voltage rank of the inkjet head 30 is determined temporarily, a reference voltage V1 for recording a reference pattern 51 is set on the basis of the voltage rank. Then, a range and an interval of a driving voltage V2 of a change pattern 52 which is recorded while coincided or deviated in the recording position with or from the reference pattern 51 are set. A plurality of the reference patterns 51 are recorded side by side by the reference voltage V1. The change patterns 52 each with the changed driving voltage are recorded overlapping with the reference patterns 51. A discrimination pattern 53 is thus formed. The driving voltage is set by distinguishing whether or not the reference voltage V1 is appropriate by a position of the discrimination pattern 53 with the most clearly drawn pattern.