A display device capable of expressing gradations with improved accuracy is presented. The device includes: a switching thin film transistor (TFT) and a driving TFT on an insulating substrate; a first electrode electrically connected with the driving TFT; a light emitting layer; a second electrode that supplies a common voltage to the light emitting layer; and a data driver that supplies the switching TFT with a data voltage ranging from a first voltage to a second voltage. The first voltage, the second voltage and the common voltage satisfy the equations: 1) First voltage−common voltage−voltage dropped by light emitting layer=black voltage±0.1|black voltage−white voltage|; 2) Second voltage−common voltage−voltage dropped by light emitting layer=white voltage±0.1|black voltage−white voltage|. The black voltage and the white voltage refer to gate-source voltages (VGS) that express the lowest gradation and the highest gradation, respectively.