An outdoor illuminating device and illuminating method using LEDs as light sources to reduce a load on the environment and effectively function as a crime deterrent to contribute to environmental design for establishing safe and secure communities. Security light (1) capable of simultaneously emitting at least two different colors of illumination light is provided with a plurality of white LEDs (16) and blue LEDs (18) as the light sources. The security light (1) comprises main lighting unit (11) positioned at a predetermined distance (D) above the ground surface (G), first illuminating part (13) for emitting illumination light of white-tint color downward in the direction substantially vertical from main lighting unit (11), and second illuminating part (14) for emitting illumination light of blue-tint color to the outside of the area substantially vertically below main lighting unit (11).