Abstract: A ceramic foam consisting of two layers in and out, in which a highly pure ceramic shell covers up the surface layer of the fly ash, is provided along with a process for producing such a ceramic foam. The process for producing a ceramic foam 10 includes the steps of: coating the surface of raw fly ash material containing impurities 12 with alumina slurry; granulating the coated fly ash; and sintering the granulated fly ash in a manner that the granulated fly ash is heated in a furnace with raising temperature, then kept at a predetermined temperature for several hours and then, slowly cooled down to room temperature. The impurities are sealed inside the fly ash 11 not to transfer to the outside so that the surface of the fly ash is covered up with a ceramic shell 13 to form the ceramic foam 10 having two layers in and out.