As beauty becomes an important aspect and the industry is growing, Korean cosmetics are trending all over the world with their advanced and developed technology and ingredients. In Southeast Asia, particularly Indonesia, Korean cosmetics is becoming the latest beauty trend that people are adding to their beauty routines. Therefore, the researcher has planned to analyze the factors influencing Effective Decision Making of Consumers in Etude House Surabaya. One hundred respondents were given a questionnaire using a six point Likert Scale. Eleven hypotheses were analyzed using the multiple regression models. The result of this study showed that independent variables Social Structure, Opinion Leaders towards Personal Information Source, Perceived Risk, and Word-of-Mouth as intervening variables to Effective Decision Making had a positive and significant effect whereas independent variable Communication Medium towards the intervening variables was negative and insignificant. The recommendation for future researchers is to add or change the variables in this study to see from different perspectives and gain new insight. For Etude House, this study can be used for evaluation purposes to further improve their marketing strategies and learn more about their consumer behavior