A method of driving light sources controls amounts of light from light-emitting diode (LED) strings based on pulse signals to operate the LED strings connected in parallel. Voltages are synchronized with the pulse signals at input terminals of control circuits to detect the voltages, the control circuits being connected to the LED strings and controlling resistance variations of the LED strings. The operation of the LED strings is stopped when the detected voltage is out of a predetermined allowable voltage range due to a short-circuited LED. Therefore, a light source device may be protected by stopping the operation of the LED strings.