A film forming device includes a mask member that is made of silicon and has first openings of predetermined patterns; a magnetic member that is made of a magnetic material and has a second opening, and that is aligned with the mask member so that the first openings are arranged in the second opening in plan view of the second opening; and a substrate holding member that generates magnetic force between the magnetic member and itself in order to adhere the mask member and a substrate to each other. The mask member and the substrate are interposed between the magnetic member and the substrate holding member in this order from the magnetic member.