A filling material for a resin composition includes a base material, a coating material coating at least a portion of a surface of a particle of the base material, and a light-reflective material disposed on the surface of the particle of the base material and supported by the coating material. The base material includes a first inorganic compound containing a Group II element. The coating material includes a second inorganic compound containing the Group II element. The second inorganic compound is different from the first inorganic compound. The light-reflective material includes a third inorganic compound having a refractive index higher than a refractive index of the first inorganic compound. A method of manufacturing the filling material is provided. A resin composition including the filling material, a package, a light-emitting device, and methods of manufacturing them are also provided.