An illuminator of plant cultivating comprises a first light source 2 for irradiating a light including red light component onto a plant P, and a second light source 3 for irradiating a light including far-red light component onto a plant P. The irradiation action of the light source 2 is controlled by a control part 4. Time zone of the control part 4 in action is set by a time setting part 5. The time setting part 5 is set in the way of making the first light source 2 perform an irradiation action in the time zone crossing sunset, and then making the second light source 3 perform an irradiation action more than 3 hours in the time zone before sunrise. Thereby, the light including red light is irradiated in the time zone crossing sunset and the light including far-red light is irradiated onto the plant P and an improvement of the growth of the plant P thus can be achieved.植物育成照明裝置1具備對植物P照射含有紅光成分的光之第1光源2,及對植物P照射含有遠紅光成分的光之第2光源3。光源2的照射動作係由控制部4控制。控制部4進行動作的時間帶係由時間設定部5設定。時間設定部5被設定成:第1光源2於涵蓋日落的時間帶進行照射動作,然後第2光源3於日出前的時間帶進行3小時以上照射動作。藉此,對植物P於涵蓋日落的時間帶照射含有紅光成分的光,然後照射含有遠紅光成分的光,因此能促進植物P之成長。1‧‧‧照明裝置2‧‧‧第1光源3‧‧‧第2光源4‧‧‧控制部5‧‧‧時間設定部6‧‧‧配電線21‧‧‧發光體31‧‧‧發光體22‧‧‧紅光濾光器32‧‧‧遠紅光濾光器F‧‧‧畝田P‧‧‧植物
