In an image forming apparatus, a quantized amount of correction A is applied to emission timing with which each light-emitting point is to be caused to give off light emission to thereby align points of exposure to light emitted from the light-emitting points, substantially with a straight line extending in the main scanning direction on a photoconductor. The amount of correction A is adjusted by adding or subtracting one to or from one of the tentatively determined amounts of correction A1, A2 for light-emitting point (P1, P2) at opposite ends of two adjacent light-emitting chips, if formula (1) is not satisfied:  Δ   E - B 