To obtain an inorganic filler which is high in mixing and dispersing property with respect to a plastic and with which a resin composition superior in thermal stability can be manufactured.

The method for manufacturing the plastic filler including a process in which an organic film originated from a coupling agent is formed on the surface of the inorganic filler by reacting the inorganic filler with the coupling agent, and a removing process in which coupling by-products are volatilized and removed by heating at a temperature of 120°C or higher, after the coupling process, is provided.