A control device and an LED light emitting device using the same are provided and technology of providing a high contrast ratio to the LED light emitting device and allowing the LED light emitting device to perform a stable operation is disclosed. The LED light emitting device includes a DC/DC converter reference voltage generator that generates a DC/DC converter reference voltage so that a minimum level of a channel voltage having a largest LED voltage drop agrees with a predetermined minimum reference voltage by detecting a plurality of channel voltages corresponding to LED voltage drops of each of a plurality of LED channels LED and an output voltage controller that controls an output voltage of the DC/DC converter using a distribution voltage corresponding to an output voltage and the DC/DC converter reference voltage.