Provided is a light emission device. When the size of an input voltage exceeds a minimum light emission voltage, all light emission elements emit light always irrespective of the size of a voltage, and as the size of the voltage decreases, the light emission device has a configuration in which the light emission elements are connected in parallel with each other, and as the size of the voltage increases, the light emission device has a configuration in which the light emission elements are connected in series with each other.