The idea of the Second Demographic Transition has gained ground among demographers who are interested in low fertility levels in developed countries. This perspective insists that people have more individualized attitudes about their life events such as careers, marriage and children. As they place more values on their own hopes and preferences, they tend to delay or avoid marriages and give less births. This study examines possible application of the Second Demographic Transition Theory by 1) analyzing the association between attitudes about marriage, children and gender roles and later childbearing behaviors and 2) tracking down the trends in attitudes about marriage and children in the 21st century. This study finds that how married women view marriage and children matters in their decisions about pregnancy and notices a recent large drop in the absoluteness of marriage even among married women, those who may be so favorable toward marriage. This study indicates that policies toward low fertility levels should pay attention to our perspectives about not just children but also competing events in life.