A new technique has been devised to find tiny quantities of manganese (II). For the spectrophotometric detection of manganese, the 4-Amino antipyrine -3, 5-diaminobenzoic acid (AAPDAB) has been proposed as a new analytical reagent. The color responses happen instantly, and for more than five hours, the greatest absorbance was found at 390 nm. The pH range from 3 to 5 is where complex formation is seen. Metal and ligand were obtained in a 1:1 (M: L) composition using the Molar ratio relationship and the Job's approach. The calibration graph had a limit of detection (LOD) of 0.15 g ml-1 and was linear in the range A390 = 0.27577 - 0.00765. In the Mn (II) concentration range of 0.126–2.628 g/ml, the system complies with Beer's law. The AAPDAB method was used to determine the presence of manganese in some plant samples since it is more sensitive.  The AAPDAB was discovered to have a molar absorptivity of 6.35 X 103 L mol-1cm-1 and a Sandell's sensitivity of 0.00157 g/ml g cm-2 of Mn (II). Manganese (II) levels in environmental plant samples have been successfully determined using the approach, with satisfactory results.