This study aims to determine the effect of social support, product knowledge, and consumer ethnocentrism on purchasing decisions of Ponorogo batik in East Java. This research is quantitative. The population of this research is teenagers who buy Ponorogo batik clothes. The number of samples in this study was 250, the sampling method used purposive sampling. Methods of data collection using questionnaires distributed to respondents online and offline, data measurement using a Likert scale 1 - 5 The method of analysis of this research is SEM (Structural Equation Modeling) with the help of statistical tools IBM SPSS AMOS 26. Results From this study it was found that social support has a positive and significant effect on increasing buying decisions, as well as consumer ethnocentrism which is found to have a positive and significant effect on buying decisions, while product knowledge in this study is found to have no significant effect on buying decisions for batik clothes in Ponorogo. These findings contribute to the development of a customer culture theory regarding ethnocentrism towards local products which can become a culture in people's behavior as a love for the local products they have. The novelty of this research is that product knowledge is not a guarantee for someone to want to make a purchase. This is because consumers do not have sufficient information about the product resulting in consumers having limited knowledge. In addition, consumers lack knowledge and tend to rely on information from other people, so it can be said that if information from other people is lacking, consumers who make purchases are also unsure about buying it.