An adjustment method executed in an image forming system including a sheet conveying portion which conveys a sheet, a plurality of nozzles arranged along a width direction orthogonal to a conveying direction of the sheet by the sheet conveying portion, and discharge elements which are respectively provided in correspondence with the nozzles and cause ink to be discharged from the nozzles in accordance with an application of a driving voltage, the adjustment method comprising:
- an image forming step of forming, using a plurality of the discharge elements, an adjustment image that is based on predetermined adjustment image data on the sheet conveyed by the sheet conveying portion;
- a reading step of reading the adjustment image formed on the sheet;
- and
- an adjustment step of adjusting the driving voltage for each of the discharge elements or in a unit of the plurality of discharge elements based on the adjustment image read in the reading step.