The rapid development of a wide range of social media such as Facebook, Twitter, Instagram Instagram as the media makes a big social network with the most rapid growth in 2014. In addition, followed by the need for cosmetic increasing among women who may be purchased by shopping online via instagram. Convenience of shopping via instagram make cosmetics as a primary need and necessity that must be worn by women. This type of research is ex post facto research. Ex post facto is a study conducted to investigate the events that have occurred and then look back to find out the factors that may cause the incident. The sampling technique used purposive sampling technique. Samples are FISIPOL UMY student who has instagram, and student FISIPOL UMY who have never shopped beauty products via instagram many as 100 students. The technique of collecting data using questionnaires. The validity of using CFA and reliability test using Cronbach alpha formula. Data were analyzed using simple regression analysis. The results showed that attitudes in social media Instagram effect on interest in shopping via Instagram. A positive attitude is determined by the student FISIPOL UMY conversation testimony contained in the instagram. If the conversation or conversations on instagram positive and widely recommended for purchase, it will form a positive consumer attitudes so that consumers will be attracted to the brand and buy it. While the conversation when exposed to the negative instagram then FISIPOL UMY student attitude will be negative and of course the testimony can weaken the brand and even encourage others not to buy the brand. A positive attitude FISIPOL UMY students showed interest in a product in social media instagram and buy it. Meanwhile, the negative attitude coed FISIPOL UMY then consumers will not be interested or interested in buying the brand.