The purpose of this study was to investigate the differences in the parenting knowledge as the socio-demographic variables of the mothers with infant and to examine the influence of socio-demographic variables on the parenting knowledge of mothers. This study was conducted with the data from ‘Panel Study Korean Children(2009),’ in which a sample of 1,637 mothers with infant whose age was ranged from 13 to 18 months participated. The major results of this study were as follows. First, the mothers with infant reported generally high level of parenting knowledge. Second, there were statistically significant differences in parenting knowledge as child's birth-order, mother’s age, mother’s educational level, mother’s employment, and family income. Lastly, the parenting knowledge of mothers with infant was influenced by mother’s educational level and family income. The results form this study suggest that it is necessary to provide differentiated approach based on mother's socio-demographic characteristics for the effective parenting education.