Ash collected from internal-circulation fluidized bed boilers, whose implementation has been promoted widely for incinerating waste or for use as coal power generation systems, was added to polypropylene resin, and the resultant material was evaluated for its practicality for use as a filler. One of the findings is that, in order to be an effective alternative to the conventional filler made of talc, there are several requirements: ensuring stable incineration within the fluidized bed, minimizing variation in ash composition, and establishing appropriate standards for ash concerning certain properties, including particular diameter, moisture content, and ratio of unburnt ash. Another finding is that while the porous construction of its ash particles contributes to improving impact resistance, it also resoults in lower rigidity, limiting its practicality for industrial use to a certain extent. Based on the findings of this study, a material made by adding ash from the fluidized bed to polypropylene was formed and processed, finding its way successfully into practical applications for automobile parts and other materials.