A reticle shape regulation device includes: an adsorption device having an upper surface and a lower surface; and a limit mechanism having a limit surface. The adsorption device is movable relative to the limit mechanism at least in a vertical direction. The upper surface of the adsorption device faces toward and is engagable with the limit surface. The lower surface of the adsorption device defines a vacuum chamber that is configured for communication with a negative-pressure source so as to adsorb the reticle by a negative pressure. The lower surface of the adsorption device further defines at least one positive-pressure outlet that is in communication with a positive-pressure source and is configured to supply a continuous positive-pressure air flow between the lower surface of the adsorption device and the reticle during the adsorption of the reticle. The positive-pressure air flow is so controlled as to form an air cushion between the lower surface of the adsorption device and the reticle while allowing the adsorption of the reticle by the adsorption device. This can correct deformations of the reticle, thus enabling satisfactory flatness thereof during an exposure process, and can easily create vacuum and an air cushion between a deformed reticle and the adsorption device.