To provide a lighting device which has little affection on plants, is easily maintained, and can efficiently protect the plants from owlet moths.

This illumination device 1 is disposed to irradiate the peripheries of the culture ridges of an orchard with light. The illumination device 1 emits the light at a light-emitting temperature of 2000 to 3000 K from light-emitting diodes 6 containing at least two kinds of metals selected from Ga, As, Al, In, P and N. An average space illuminance in the orchard is controlled to about 11x to prevent the invasion of the owlet moths in the orchard. When the average space illuminance is ≥101x, the growth of the plants are affected. Thence, the average space illuminance is maximally controlled to about 101x.