A pixel arrangement structure of an organic light emitting diode (OLED) display is provided. The pixel arrangement structure includes: a first pixel having a center coinciding with a center of a virtual square; a second pixel separated from the first pixel and having a center at a first vertex of the virtual square; and a third pixel separated from the first pixel and the second pixel, and having a center at a second vertex neighboring the first vertex of the virtual square. The first pixel, the second pixel, and the third pixel have polygonal shapes.