A display device includes data lines and pixels. Each pixel includes a driving transistor, a switch between one of the data lines and a gate of the driving transistor, and a luminescence element connected to the driving transistor. A first circuit path former flows a first test current from the one of the data lines through the first transistor and a second test current from the one of the data lines through the luminescence element. A second circuit path former generates a first voltage and a second voltage in the one of the data lines. The first voltage corresponds to a gate voltage of the first transistor generated by the first test current. The second voltage corresponds to a luminescence voltage of the luminescence element generated by the second test current. A voltage detector detects the first voltage and the second voltage in the one of the data lines.