Research Aims: to explore behavioral biases of stock investors in their decision making and find which bias is the most often experienced by Indonesia investor. Investor behavior plays an important role in making investment decisions in the capital market. The less the biases, the better the decision.Design/methodology/approach: Using qualitative approach, semi-structure interview was conducted with 5 Indonesia investor. All five participants are Indonesian and aged between 34-69 years old. The interviews begin with some general questions and are followed by addressing more questions arising from the previous discussion. The transcriptions of interviews from respondents use the verbatim approach.Research Findings: Several biases that we have found are herding, loss aversion, disposition effect, anchoring and availability biases. Herding is the one that happens more often. From those 5 behavioral biases from the result of the interviews, herding is the one that happens more often. This study suggests that herding is note-worthy, that is, this bias needs to be explored more deeply. This research also found that better educational background and knowledge can reduce the biases in decision making.Theoretical Contribution/Originality: This research was using qualitative approach explore investor bias in Indonesia. Keywords: Investor bias, herding, risk aversion, disposition effect, anchoring and availability