PROBLEM TO BE SOLVED: To provide a plant growing light source unit capable of supplying a sufficient quantity of light and performing subtle adjustment of the quantity of light and a wavelength in growing plants and having excellent maintenance performance.SOLUTION: The plant growing light source unit includes a light source part 2 emitting a growth promoting light and a light transmitting part 3 including a window member 31 for transmitting the growth promoting light. The light source part 2 is disposed on a main surface of the window member 31 and includes electrode lines wherein a plurality of pairs of parallel plate electrodes 23 made of a pair of electrode plates are arranged in a parallel direction to the main surface of the window member, and a high-frequency power source 22 applying a high frequency for generating plasma served as a light source, between each of the pairs of parallel plate electrodes.【課題】 植物の育成において、十分な光量の供給、光量や波長の微妙な調整が可能であり、かつ、メンテナンス性も良い植物育成光源ユニットを提供すること。【解決手段】 成長促進光を発する光源部２と、成長促進光を透過させる窓部材３１を含む光透過部３と、を備え、光源部２は、窓部材３１の主面上に配置され、電極板の対からなる平行平板電極対２３が窓部材の主面と平行な方向に複数対並べられた電極対列と、各平行平板電極対間に光源となるプラズマを発生させるための高周波を印加する高周波電源２２とを含む。【選択図】図２
