A manufacturing method includes: a dry mixing step of dry mixing a raw material by batch processing; a wet mixing step of adding liquid to a dry mixture obtained at the dry mixing step, the liquid including at least one type of water, surfactant, lubricant and plasticizer, while wet mixing; a kneading step of kneading a wet mixture obtained at the wet mixing step; and a forming step of extruding a kneaded mixture (forming raw material) obtained at the kneading step to make a ceramic formed body. In the kneading step, the liquid is further added during kneading of the wet mixture.