PROBLEM TO BE SOLVED: To provide an ultraviolet absorber having high ultraviolet absorbing ability in both UVA and UVB regions using a lignin which is a circulation type biomass.SOLUTION: There is provided an ultraviolet absorber containing a lignin decomposed product obtained by a production method comprising the following steps (1) to (3). Step (1): a step of saccharifying a lignocellulose raw material by an enzyme to obtain a saccharification residue. Step (2): a step of heating the saccharification residue obtained in the step (1) in an aqueous solvent or in a mixed solvent containing an organic solvent having a solubility to water at 20°C of 90 g/L or more and water to obtain a heat-treated liquid containing a lignin decomposed product. Step (3): a step of solid-liquid separating the heat-treated liquid obtained in the step (2), followed by removing insoluble matters to obtain the lignin decomposed product.【課題】循環型バイオマスであるリグニンを利用した、ＵＶＡおよびＵＶＢ両領域の紫外線吸収能が高い紫外線吸収剤を提供する。【解決手段】下記工程（１）～（３）を有する製造法によって得られるリグニン分解物を含有する紫外線吸収剤。工程（１）：リグノセルロース原料を酵素により糖化処理して糖化残渣を得る工程工程（２）：工程（１）で得られた糖化残渣を、水溶媒中、または２０℃の水に対する溶解度が９０ｇ／Ｌ以上の有機溶媒と水とを含む混合溶媒中で加熱処理して、リグニン分解物を含有する加熱処理液を得る工程工程（３）：工程（２）で得られた加熱処理液を固液分離して、不溶分を除去し、リグニン分解物を得る工程【選択図】なし
