Purpose: This study aimed to identify the effect of fetal attachment and pregnancy on health promoting behavior in primigravida. Methods: The subjects were 149 primigravidas who enrolled in nationwide online cafe for pregnant and childcare women. The data were collected from February, 2008 to February, 28 in 2022. The collected data were analyzed by IBM SPSS Statistics ver. 24.0. Results: The primigravidas’ health promoting behavior was significantly affected by the fetal attachment (β=0.37, p<0.001), spouse stress (β=0.32, p<0.001), subjective health condition (β=0.28, p<0.001), academic background (β=0.25, p<0.001), primigravidas themselves stress (β=-0.24, p=0.001), and monthly income (β=0.18, p=0.005). These variables explained 41.5% of the variance in health promoting behavior. Conclusion It is necessary to seek out how to improve the fetal attachment through interactions with fetus, for enhancing primigravidas’ health promoting behavior and to develop a program by educational levels, for forming positive mind about health. Moreover, various efforts and strategies are required to reduce the pregnancy stress and enhance the health of both primigravidas and fetus, by early detecting and alleviating the pregnancy stress.