To provide a concentration unevenness correcting method of an image recording apparatus which corrects concentration unevenness without repeating maintenance processing and recording of test patterns even when there is random MF.

A part where the image concentration has a value lower than a predetermined value is detected from a test pattern recorded by the image recording apparatus. When it is determined that the part where the image concentration has a value lower than the predetermined value is caused by defective ink discharge, the concentration information of the nozzle which defectively discharged ink is replaced by the concentration information of a nozzle which is at a position in the periphery of the ink-defectively-discharged nozzle in the concentration unevenness correcting method.