The birth rate in Korea has sharply decreased since 1995, and the average birth rate was 1.17 children per woman in 2002. So the phenomenon of having few children is more severe than at any other time. The purpose of this research is to find the cause of it. To obtain this goal, I investigated the relationship between mothers' consciousness about the birth and rearing of children and a variety of factors, such as taking a job, age, and the level of education, for 592 women. According to the survey, not only economic matters, but also a change of consciousness about the value of marriage and bringing up children is deeply related with the reason Korean mothers have the low birth rate recently. In addition, the survey showed that if they have a job, they are young, or they have a high level of education, the change of consciousness was very distinctive.