A mother substrate for an organic light-emitting display device includes a base substrate, a plurality of display areas arranged in an array on the base substrate, the array having a plurality of rows and a plurality of columns that are perpendicular to the plurality of rows. The mother substrate further includes a plurality of first dummy patterns formed between the plurality of rows of display areas, and a plurality of second dummy patterns formed between the plurality of columns of display areas. The plurality of first dummy patterns are spaced apart from each other by a plurality of cut portions.