Disclosed herein is a voltage control circuit for a dimmer and a dimming method. In accordance with an embodiment, the dimming method using a voltage control circuit for a dimmer includes the steps of determining whether a current voltage value input to a constant dimming range maintainer is equal to a preset minimum or maximum voltage value or exists between the minimum and maximum voltage values, and determining whether the current voltage value is greater than the maximum voltage value when the current voltage value isn't equal to the minimum or maximum voltage value or doesn't exist between the minimum and maximum voltage values. The method further includes the steps of updating the minimum voltage value to the current voltage value when the current voltage value isn't greater than the maximum voltage value, and updating the maximum voltage value to the current voltage value when the current voltage value is greater than the maximum voltage value.