This LED lighting device is provided with a control circuit (2) which controls the ON/OFF state of a switching element (Qa1) such that the LED current in an LED unit (LEDa1) is within a rated current range. When the LED unit (LEDa1) is illuminated, the voltage applied to both ends of the series connection between a reactor (La1) and the LED unit (LEDa1) is set to a first bus voltage (V1) when the switch element (Qa1) is ON, and, when a switch element (Qa2) is OFF, is set to a voltage below the first bus voltage (V1), determined on the basis of the first bus voltage (1) and a second bus voltage (V2).