People frequently choose packaged drinks. Besides being practical, packaged beverages are easy to obtain. One of the most popular packaged beverages among Indonesian people is liquid milk. The milk brand being studied by the author is Ultra Milk. This is because Ultra Milk had an increase in sales in the third quarter of 2023 but declined on the Top Brand Award over the last two years. This research aims to determine the influence of Instagram's Social Media Marketing Activities (SMMA) on the purchase intention of Ultra Milk. This study uses quantitative methods. The data analysis method uses structural equation modeling (SEM-PLS) analysis techniques which are processed using SmartPLS 4.0 with a total of 385 respondents that had several criteria. This study sample is purposive sampling, with questionnaires distributed using Google Forms. Based on the processed data, it has been determined that Social Media Marketing Activity (SMMA) has a positive impact on brand equity. Furthermore, brand equity positively impacted e-WOM, and e-WOM positively influenced customer purchase intention. Lastly, Social Media Marketing Activity (SMMA) showed a direct impact on customers' purchase intentions. Keywords: Social Media Marketing; Brand Equity; E-WOM; Purchase Intention