This research is a survey research. With the purpose to study the decision making behavior to buy cosmetics direct sales system of undergraduate students. Using the questionnaire as a tool to collect information. By way of a random sample from the formula of Taro Yamane number of 381 people. The statistics used in data analysis, percentage, mean, standard deviation, and Chi-square Test. An analysis of the data showed that. Most of the respondents are female. Revenue 6001-8000 baht per month. The buying behavior of cosmetics. Mainly to buy cosmetics brand marketing Mistine most. Makeup Products category. From a cosmetic shop. The decision to buy cosmetics Direct selling system. Mainly to strengthen the personality. And the reason for the decision to add beauty, buying when cosmetics that use is low. In the product price and the campaign to influence decision making in many levels