The present invention relates to an LED driver for driving a plurality of light emitting diodes (LEDs), comprising a current controller to control power supply of a predetermined power source unit to make a current flowing in the plurality of LEDs reach a predetermined target current value which sequentially changes corresponding to the respective LEDs; a plurality of divergence switches to flow or interrupt the current with respect to each of the plurality of LEDs; a bypass switch being connected in parallel with respect to the plurality of divergence switches and the plurality of LEDs and to flow or bypass the current supplied to the plurality of LEDs by being open or short-circuited; and a switch controller to sequentially open and close the plurality of divergence switches corresponding to change of the target current value and control the bypass switch to be short-circuited in a range where the current supplied to the LEDs increases, corresponding to the rise of the target current value. Thus, the present invention provides an LED driver which drives an LED in a low voltage to improve light efficiency.