A medicament for prevention and remedy of disorders of decrease in the number of blood corpuscles such as leukocytes, reticuloctyes and thrombocytes (blood platelets) and the use of this medicament are disclosed. The medicament contains as an effective ingredient thereof a nonapeptide having the following amino acid sequence: pGlu-Ala-Lys-Ser-Gin-Gly-Gly-Ser-Asn or an ester or an amide at the carboxyl group of the C-terminus of the asparagine or a pharmacologically acceptable salt thereof or a derivative thereof combined with a metal. This medicament is utterly non-toxic to human and animals and effective for prevention and remedy of disorders of decrease in the number of blood corpuscles such as leucocytes caused by administration of chemotherapeutics agents such as anti-cancer agents or accompanied by cancer or viral diseases.