An organic light emitting diode (OLED) display device includes a display panel including a plurality of OLED pixels arranged in a matrix form to display an image, and the plurality of OLED pixels each includes a switching thin film transistor (TFT) to switch a data voltage pass supplied from a data line in response to a scan signal input through a gate line, a driving TFT turned on in accordance with a magnitude of a data voltage supplied from the switching TFT to control an amount of light emitted from an OLED, and a variable storage capacitor connected in parallel to a gate electrode of the driving TFT and having a capacitance varying in accordance with a magnitude of a voltage applied to the gate electrode of the driving TFT may increase a charging speed and a charging rate of a data voltage of the OLED pixel. As a result, it is possible to improve threshold voltage compensation efficiency and solve a problem such as non-uniform luminance and an afterimage.