Based on social capital theory, this study aims to examine the effect of social capital domains on an individual's learning and cognitive attitude which regulates decision-making to purchase. Individuals who socially interact with each other and share vision using social media are more likely to share their purchase recommendation, which cognitively motivates to make a purchase decision where trustworthiness among networks strengthen the relationship of social interaction, social vision and cognitive behaviour of an individual. With the help of latest literature, theoretical model and number of the hypothesis are built. Data was collected from 360 universities students who use social media to collect for information and knowledge and ask for a recommendation from their social capital, on which, they trust while purchasing products and services. AMOS-21 was used to perform statistical analysis, and where for moderation analysis, hierarchical regression method is used.