In recent years, social media development has changed the advertising and marketing landscape and has turned into a tool that businesses would do well to exploit. In 2019-2020 the growth of postpaid users has decreased. To increase user growth and understand the factors that influence consumer buying interest, companies need to know the key factors that can increase purchase intentions, in order to formulate a better marketing strategy. This study aims to determine the influence of marketing on social media with the variables of quality of social media, quantity of social media, and credibility of social media on customer inspiration and customer purchase intention. The method used in this study is a quantitative method. The questionnaire distributed to 384 consumers from prepaid users who have Instagram and have seen Telkomsel Halo content on Instagram. Sampling was carried out using a non-probability sampling method of purposive sampling. The data analysis technique uses SEM – PLS (Partial Least Square) which is processed using SmartPLS software. It was found that customer inspiration has a positive and significant effect on purchase intention. The indirect effect on purchase intention is also found credibility of social media marketing has a positive and significant effect on purchase intention.