Exclusive breastfeeding is providing food for infant only breastmilk without any liquid or other solid substances including water, except vitamins, minerals, and medicine. The World Health Organization (WHO) recommends exclusive breastfeeding for up to six months. In 2016 Exclusive Breastfeeding coverage in Indonesia was still below the national target (80%). The purpose of this study was to determine the factors related to exclusive breastfeeding in the working area of the Air Dingin Primary Health Center in 2018. A cross-sectional study was conducted in the working area Air Dingin primary health center from February to September 2018. The sample of this study was mothers who had children aged 6-12 months as many as 115 people who met the inclusion criteria. Mothers as respondents were interviewed directly using a questionnaire. The analysis was carried out by chi-square statistic test and multivariate analysis used multiple logistic regressions. Results of this study obtained 63.5%, not exclusive breastfeeding. Factors that influence are good knowledge (81.7%), positive attitude (89.6%), high education (74.8%), no interest in the promotion of formula milk (69.6%), supporting health workers (91,3%). There is a relationship among knowledge (p = 0.002), level of education (p = 0.007), attention to formula milk (p = 0.008) of exclusive breastfeeding. In contrast, there was no relationship between attitudes (p = 0.053) and support from health workers (p = 0.322) with exclusive breastfeeding. Multivariate analysis obtained the dominant variable is known.