To provide an image forming apparatus decreasing a reciprocity law failure by interlace and avoiding the occurrence of banding caused by scanning line bending interference having a trade-off relationship to the decreasing of the reciprocity failure.

In the image forming apparatus, a plurality of pairs of scanning lines are configured by making two scanning lines which are adjacent to each other and different in scanning times as one pair of scanning lines such that portions of scanning lines which are simultaneously formed on a photoreceptor overlap the portions of the scanning lines formed by different scanning, while shifting positions. Then, curving of the scanning lines is corrected by exposure intensity distribution between the pairs of scanning lines.