A method of manufacturing a flat panel display is disclosed. In one aspect, the method includes preparing first and second mother substrates, forming a plurality of display cells on at least one of the mother substrates, forming a plurality of sealant lines enclosing the respective cells on either one of the mother substrates and assembling and sealing the two mother substrates with the sealant lines interposed therebetween. The method also includes mounting the two mother substrates on a stage, irradiating a laser beam to a defined light irradiation region of the mother substrates and cutting the mother substrates while moving the light irradiation region along an imaginary cut line where the mother substrates are to be cut. The light irradiation region includes a linear region and a curved region.