An organic light emitting diode (OLED) display device including a first transistor configured to supply a data voltage to a first node according to a scan signal; a first capacitor connected to the first node at one end of the first capacitor, and connected to a second node at the other end; a second transistor configured to supply a reference voltage to the second node according to a sensing signal; a driving transistor including a drain electrode receiving a high-level source voltage or an initial voltage, a gate electrode connected to the second node, and a source electrode connected to a third node; and an OLED including a cathode electrode receiving a low-level source voltage and an anode electrode connected to the third node.