An electron emission display and a driving method thereof adjust a brightness differently according to a brightness of a frame in order to reduce power consumption and prevent a gradual failure from occurring, and easily recognize a change of the brightness. A pixel portion receives a data signal and a scan signal, and displays an image. A data driver generates the data signal using video data and transfers the data signal to the pixel portion. A scan driver transfers the scan signal to the pixel portion. A timing controller transfers a drive signal to drive the data driver and the scan driver, to the data driver and the scan driver. A data processor generates a control signal corresponding to frame data obtained by summing a value of video data inputted during one frame. A power supply section generates a drive voltage and transfers the drive voltage to the pixel portion, the data driver, the scan driver, the timing controller, and the data processor. A brightness of the pixel portion is changed according to the control signal, and a change amount of the brightness is changed according to a hysteresis curve.