Fail investment decisions have the impact of bankruptcy or failure. The intention of the research is to seek and explore interaction demographic moderateness influences herding and confirmation bias to determine investment decision’s youth investor. The research used three-way ANOVA analysis techniques. There were 467 respondents who completed the survey in full and regress by SPSS with additional tool process. The aims of the research are to investigate interaction among herding bias and demographic factors affect to investment decision of young investor. Initial step is to investigate effect of herding bias to investment decision, then investigate interaction among herding bias to both each demographic, consist of gender and religion toward investment decision. Collecting data using questionnaires referring to the concept of finance behavior. The novelty of this research come from limited and complexity method, also the result of research to examine interactions between the two levels of moderation. The research reveals that youth investors’ investment decision is influenced by herding bias. Further, there are interaction among herding bias and demographic factors toward investment decision. The younger generation must be rational to determine to prevent herding bias, including their demographic features.