A plasma display calculates a screen load ratio from a plurality of video signals input during one frame, determines a total number of sustain pulses of the frame according to the screen load ratio, and determines a number of sustain pulses allocated to each subfield from the total number of sustain pulses. In addition, the plasma display divides a first number of sustain pulses allocated to at least one of the plurality of subfields into a second number of sustain pulses having a first period and a third number of sustain pulses having a second period different from the first period.