To easily discriminate presence and kind of error from an exposed plate by changing position or form of the exposure region of substrate according to the kind of error at exposure when an error takes place in a pre-process for exposure.

Corresponding to an error A, combination of projection lenses for the light path for exposure is alternately provided, related to the lighting region of lighting light on a plate, for exposure. With execution of reject exposure to an error B judged, the reject exposure is ordered to a lighting system and carriage control system at execution. The scan range for exposure is set to an intermediate point, corresponding to the error B, for exposure. As a result of the reject exposure, the plate is exposed with a pattern in which, being definitely different from the error A, about a half region in the scanning direction is an exposure part E1 while the remaining region a non-exposure part E2, corresponding to the error B. A characteristic exposure pattern is provided to the plate corresponding to the errors A and B which took place, and the presence and content of error is discriminated by observing a pattern after development.