Background: Breast milk is the only recommended and best food, cheap and easy to obtain for babies. Although breastfeeding does not cost money, the percentage of exclusive breastfeeding is still far from the target.Objectives: The study aimed to measure the relationship, advertisement of formula milk and exclusive breastfeeding in infants 6-12 months.Methods: This research is analytical in nature using a cross sectional design. The research sample was a total population of 58 people. The study was conducted in February 2020. Data collection used a questionnaire form and interview procedures were carried out. Data processing is based on grouping, namely good and poor knowledge, milk advertisements are affected and not, and breastfeeding variables are exclusive and not. Data analysis used Chi-square statistical test.Results: The results showed that 44.6% of infants were not exclusively breastfed, and 64.3% of breastmilk production was not sufficient, besides that there were 48.2% of people affected by advertisements for formula milk. The statistical results showed a significant relationship between knowledge (p= 0.015), formula milk advertising (p= 0.001), and milk production (p= 0.006) and exclusive breastfeeding for infants. Formula milk advertisement variable is the variable most associated with exclusive breastfeeding for infants 6-12 months. Conclusion: There is a relationship between knowledge, advertising for formula milk and breast milk production with exclusive breastfeeding for infants. Advertising for formula milk is the dominant variable in the low coverage of exclusive breastfeeding.