In the present invention, when exposure on a first exposure area of the subject to be exposed by using a first mask pattern group of a photomask, is completed, the shutter is moved in synchronization with a conveying speed of the subject to be exposed to shut off source light, the subject to be exposed is returned by a distance in which the subject to be exposed moves while the shutter moves, and the mask pattern group is switched to a second mask pattern group by moving the photomask. When the switching of the mask pattern group of the photomask is completed, the conveying of the subject to be exposed is restarted. At the same time, the shutter is moved in synchronization with the conveying speed of the subject to be exposed to release the shut off of the source light, and exposure on a second exposure area is performed.