An image color correction method and an image forming apparatus are provided, which are capable of correcting an image color with much higher accuracy. A first light (red light) is irradiated on patch image (for example, an image of cyan color) formed on a sheet by the image forming apparatus, and a second light (red light) is irradiated on the vicinity of the patch image on the sheet, respectively by the image forming apparatus. The light amount of the second light is adjusted so that the brightness of the second light coincides with the brightness of the patch image irradiated by the first light. Based on the light amount adjusted for correcting the color of the image outputted by the image forming apparatus, the image forming condition of the image forming apparatus is set.