A scanning exposure apparatus measures levels of a substrate at a predetermined position on the substrate during an acceleration period and during a constant velocity period, obtains a correction value for a measurement error due to factors associated with acceleration based on the difference between the measurement results at the predetermined position, corrects the level of the substrate measured at a first measurement point using the obtained correction value when the substrate is exposed at a given position after the level of the substrate at the given position is measured at the first measurement point during the acceleration period.