PROBLEM TO BE SOLVED: To provide: an ultraviolet ray absorber that has an excellent light resistance while effectively blocking long wave ultraviolet rays up to the wavelength of around 400 nm； an ultraviolet ray absorber in which said compound further effectively transmits light having a wavelength in the visible light region while blocking long wave ultraviolet rays up to wavelengths around 400 nm.SOLUTION: Provided is an ultraviolet ray absorber dispersion containing microparticles of 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one derivative represented by the general formula (I), and said dispersion has an absorption peak at a wavelength of 380 nm to 400 nm.SELECTED DRAWING: Figure 1【課題】長波紫外線を４００ｎｍ付近の波長まで効果的に遮蔽し、優れた耐光性を有する紫外線吸収剤の提供。当該化合物は、さらに、長波紫外線を４００ｎｍ付近の波長まで効果的に遮蔽しつつも、可視光領域の波長の光を透過する紫外線吸収剤の提供。【解決手段】一般式（Ｉ）で示される２，２’－（１，４－フェニレン）ビス－４Ｈ－３，１－ベンゾオキサジン－４－オン誘導体の微粒子を含有する紫外線吸収剤分散体であって、３８０ｎｍ～４００ｎｍの波長の吸収ピークを有する分散体。【選択図】図１
