Galactosemia is a metabolic disorder inherited by the recessive autosome, and appears by the deficiency of one enzyme out of GALT (Galactose-1-Phosphate Uridyltransferase), GALK (galactokinase), and GALE (epimerase) enzymes, among which the GALT deficiency disease is denominated as classical galactosemia and known to have symptoms such as severe nausea, jaundice, hepatomegaly, sucking difficulty and so on. We report the case of a 16-day-old female baby with the new p.A101D mutation together with p.N413d in the GALT gene analysis found in the neonatal screening test and diagnosed to have galactosemia by the GALT deficiency through the enzyme analysis. For the prognosis prediction, the treatment, the genetic counseling and the prenatal diagnosis of the patients, more detailed genetic diagnosis is required by performing GALT gene analysis, and it is deemed to be necessary to analyze the correlation between the phenotype and the genotype of the domestic galactosemia patients.