To provide a method for producing calcium carbonate being usable as a pigment for coating paper and having high whiteness from lime sludge produced when quicklime or a slaked liquor obtained by reacting quicklime with a sodium hydroxide-containing liquid is added into green liquor obtained at a pulp production step in a kraft method and causticized.

In the method for producing calcium carbonate from the lime sludge produced when the green liquor obtained at the pulp production step in the kraft method is causticized with quicklime or the slaked liquor obtained by reacting quicklime with the sodium hydroxide-containing liquid, it is characterized by that lime supplemented from the outside of a system is used as a quicklime source.