This study was conducted to examine the predicting factors for the intention of breastfeeding with The Theory of Planned Behavior. The questionnaires were distributed to 131 primigravidas who were in their third trimester of pregnancy in Seoul, Kyonggido, Kyongsangbukdo, and Kyongsnagnamdo. Descriptive statistics, Pearsons Correlation and Multiple Regression were used to analyse the data. The subjects showed strong intention of breastfeeding. The subjects showed favorable attitudes toward breastfeeding. This fact showed significant correlation with the belief that their breastfeeding intention was due to the advantage of breast milk for the infant with regard to allergy prevention, disease protection, contribution to intellectual development, psychological closeness between mother and infant, convenience, cost, and the reduction of breast cancer risk and weight of the mother. No item of outcome evaluation did showed significant correlation with behavioral intension. The subjects were influenced about breastfeeding by their referents such as siblings and friends with breastfeeding experience, their mothers and husbands, and mothers-in-law. Most items of the control beliefs had a significant influence on the intention of breastfeeding. The subjects felt they could not control the situation ie. "when I have to breastfeed in public". However they felt they could control the situation ie. "when I suffer from mastitis", "when I have to cut down on coffee, alcohol, and smoking", "when I have Caesarean section", "when I need to maintain breast condition", and "when the infant hates to suck my nipple". Regression analysis revealed that control beliefs and attitudes toward breastfeeding could predict the behavioral intention of breastfeeding. Control beliefs were the most important factor in predicting behavioral intention. Therefore, nutrition education is needed to enhance the ability to cope with difficult situations while breastfeeding and increase faborable attitudes toward breastfeeding.eding and increase faborable attitudes toward breastfeeding.