A plasma display apparatus is provided. Polygonal discharge cells are arranged in delta. Extension parts are extended from pairs of sustain electrodes that apply a voltage to the discharge cells to discharge spaces to face each other. Since the extension parts have at least one depressed parts, the efficiency of sustain discharge improves due to a long gap. Since the width of data electrodes formed under the discharge cells is large in the discharge spaces, a distance between the effective side surfaces of the pairs of sustain electrodes and the data electrodes is reduced so that the efficiency of address discharge improves.