Problem to be Solved An agent for ameliorating and/or preventing anemia, which is useful in the amelioration and/or prevention of cancerous anemia, and can improve the quality of life of a cancerous anemia patient without advancing cancer progression, is provided. Solution An agent for ameliorating and/or preventing cancerous anemia containing 5-aminolevulinic acid (ALA) or a derivative thereof, or a salt thereof is prepared. Preferably, a metal-containing compound such as sodium ferrous citrate is contained in these ALAs. As the above-mentioned ALAs, ALA; various esters such as ALA methylester, ALA ethylester, ALA propylester, ALA butylester, and ALA pentylester; and hydrochlorides, phosphates, and sulfates, and the like of these ALA esters can be preferably exemplified.