PROBLEM TO BE SOLVED: To provide a method and an apparatus enabling non-contact measurement of the concentration of nitrate ion and nitrite ion, and a plant growth and prolongation agent manufacturing apparatus, which incorporates the apparatus.SOLUTION: A concentration detection apparatus includes: an inspection area forming unit 1 capable of passing or storing liquid for concentration detection in an air gap 13 formed by an appropriate gap with wall surfaces 11 and 12 which can at least transmit 1% or more of light having a wavelength of 200 nm to 400 nm; light sources 2 and 3 emitting light at least within wavelength ranges of 270 nm to 330 nm and of 350 nm to 400 nm so that the light passes through the inspection area forming unit from outside the wall of the inspection area forming unit; and light detecting units 4 and 5 for detecting the intensity of light transmitted through the inspection area forming unit. A plant growth and prolongation agent manufacturing apparatus comprises a concentration detection apparatus and plasma irradiation means.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2019,JPO&INPIT【課題】 硝酸イオンおよび亜硝酸イオンの濃度を非接触によって測定することができる方法および装置と、当該装置を組み込んだ植物の生長・延命剤製造装置を提供する。【解決手段】 濃度検出装置は、少なくとも波長200nm~400nmの光を1%以上透過できる壁面11,12によって適宜間隔の空隙13が形成され、空隙に濃度検出対象の液体を通過または保存可能とする検査領域構成部1と、検査領域構成部の壁面外方から検査領域構成部を透過させるように、少なくとも波長270nm~330nmおよび波長350nm~400nmの範囲内にある光を放出する光源2,3と、検査領域構成部を透過した光の強度を検出する光検出部4,5とを備える。植物生長・延命剤の製造装置は、濃度検出装置とプラズマ照射手段とで構成されている。【選択図】 図1