The purpose of the research was to examined whether the development of babies may depends on their parents' demographic variables and identity what factors may affect that of babies. We tested abilities of babies individually by BAYLEY, WPPSI, and PPVT. The subjects of this study were 309 babies(boies: 161, girls: 148) who were members of five daycare-services centers, managed by University of Ulsan, and their mothers. The results were the followers: First, of babies' variables(sex, age, order-birth), in the percentile of PPVT girls was higher the boys. As older. the babies had higher on the cognition scores of BABLEY and the performance IQ scores of WPPSI. And on the Verbal IQ scores full IQ scores of WPPSI, the first order babies were higher than the second-birth order ones. Second, of parents' variables(age, education. income), we could not find out significantly difference in parents' education variable. However, as father's educational level was higher, their baby was higher on Verbal and Full IQ scores of WPPSI. And as mother's educational level was higher, their baby was higher on Verbal and Full IQ scores of WPPSI and the percentile of PPVT. On occupational variable, the baby whose parents' job was of white-color ones was higher on Verbal and Full IQ scores and than one whose parents' job was of blue-color ones. Third, babies' developmental levels, tested by WPPSI and PPVT, were affected by babies' and parents' variables. The Cognition score of BABLEY was affected by baby's age, Verbal IQ score was affected by baby's birth-order and father's education, and Performance IQ score did by baby's age. Full IQ score of WPPSI was influenced by baby's age, birth-order, father's education, and the percentile of PPVT was did only by baby's sex. In summary, this results suggested that as older, baby had some advantages in development levels. And the first-order baby got benefits in compare with the second birth-order one. In particular, the previous studies, which reported babies' abilities affected by mother's variables but this research was identified that baby's development was affected by father's occupation and education variables.