A limited current circuit of this invention comprising: a transformer that raises an alternating current (AC) power supplied from the digital inverter to an AC voltage of a high voltage to light a lamp; a voltage/current detection unit that detects at least one of the current and voltage supplied to the lamp; an A/D converter that converts the detected voltage/current value of analog to a digital value; and a microcontroller unit (MCU) that induces an LCC check point after the start of a striking process, compares at least one of the output current value and voltage value from the transformer with a preset reference value on the basis of an output signal of the A/D converter and then shuts down the inverter when the output current value or voltage value is determined to be abnormal, wherein the reference value comprises at least one of the current value and voltage value measured at the LCC check point when an object having noninductive resistance is not contacted to the inverter.