The invention provides an acrylic acid series resin particle capable of forming an optical material with uniform light diffusion property, a coating combination and the optical material. The acrylic acid series resin particle is characterized in that: value alpha, value gamma and value eta meet a predetermined relationship, and CV value is 30-40%, meanwhile value A is less than 0.75, and value B is 1.1-1.6, wherein the value alpha is cumulative 10% particle size by volume basis/ cumulative 10% particle size by count basis, the value gamma is cumulative 50% particle size by volume basis/ cumulative 50% particle size by count basis, the value eta is cumulative 90% particle size by volume basis/ cumulative 90% particle size by count basis, the CV value is particle size by volume basis, the value A is cumulative 10% particle size by volume basis/ cumulative 50% particle size by volume basis, and the value B is cumulative 90% particle size by volume basis/ cumulative 50% particle size by volume basis.