PROBLEM TO BE SOLVED: To promote rooting, enhance root-taking, and shorten a growing period in plant cultivation in which plants are multiplied by cuttage.SOLUTION: An illumination apparatus for plant cultivation comprises a light source section 24 which irradiates plants 12 with light. Nighttime supplementary lighting is performed to the plants immediately after cuttage is executed. In the irradiation by the light source section 24, nighttime irradiation is performed until a delivery stage by using light-emitting diodes whose emission dominant wavelength emits green light. Further, in a period from a cuttage process until pinching is executed, nighttime irradiation is performed by using light-emitting diodes whose emission dominant wavelength emits blue light or bluish green light. Therefore, rooting of the plants is promoted, and plant cultivation in which the entire plants is well balanced and has small variation can be performed.
