A process for reforming the fly ash, including the heating step that heats a raw fly ash powder containing the unburned carbon at a temperature of 780 to 1000° C. to decrease the amount of the unburned carbon contained in the raw fly ash powder; the classifying step that introduces the heat-treated fly ash containing the unburned carbon in decreased amounts obtained through the heating step into a classifying apparatus in the state of being heated at a high temperature so as to separate the fly ash into a coarse powder and a fine powder; the fine powder recovering step that recovers the fine powder of the heat-treated fly ash obtained through the classifying step by using a dust-collecting apparatus; and the milling step that mills the coarse powder of the heat-treated fly ash obtained through the classifying step until a 45 μm sieve residue becomes not more than 34% by mass, and then recovers the milled powder.