This research aims to analyze the interest of social media users in promotional activities. The design method in this research is a questionnaire for data collection and three variable factors, ease of use factor, content factor and feature usage factor, as a determinant of the interest of social media users. The analysis method uses SEM - PLS method and grouping the data with the k-means clustering data mining method. In this research, the interaction with using features in promotional activities affects user interest. The result show that ease of use does not significantly affect user interest. and the user content also does not significantly affect user Interest, but usage Features significantly affect user interest. The research conclusion is that the ease of use and content factors on Instagram does not significantly affect, and the feature factors in Instagram that are used have a significant influence.