In this exposure system, alignment marks on a photosensitive material are photographed with a reading unit. Prior to this photographing, a standard board, having detection marks at positions readable to the reading unit at preset intervals along the movement direction of the reading unit, is provided. At least one of the detection marks is photographed with the reading unit, which is arranged in a position to photograph the alignment marks provided on the photosensitive material. Calibration data is calculated based on data on the camera optical axis deviation obtained by this photographing. Standard position data reflects the calibration data, whereby calibration of the exposure position adjustment function of the exposure device is performed.