Disclosed is a pixel circuit which facilitates to compensate a threshold voltage of a driving transistor for controlling an operation state of a light emitting device, and a method for driving thereof and an organic light emitting display device using the same, wherein the pixel circuit includes a light emitting device including an organic light emitting cell; a driving transistor which controls an operation of the light emitting device according to a voltage applied between gate and source terminals; a capacitor including first and second terminals; a switching unit which initializes the capacitor during a current horizontal period, stores a sampling voltage in the capacitor, and makes the light emitting device emit light on the basis of the sampling voltage stored in the capacitor whenever the data voltage and reference voltage are supplied to the data line after the current horizontal period.