The study examined the influence of investment decision behavior on individual Islamic investors in the real and financial sectors because there are few studies on Muslim groups who invest in the real and financial sectors. Most of the research on investment decisions focuses on the capital market. This research tests psychological theories: heuristics prospects, market, and herding effect. The methodology used in this study is the structural equation method and uses primary data from 303 Islamic investors in East Kalimantan Province. The results show Individual Islamic investors' investment decision behavior in the real and financial sectors was significantly influenced by heuristics, prospects, and market factors. In contrast, the herding had no significant influence on Individual Islamic investors' investment decision behavior in the real and financial sectors. The theory of heuristic, prospect, and market factors can describe the behavior of individual Muslim investors in making investment decisions in the real and financial sectors in East Kalimantan Province, where this behavioral theory research is widely conducted in financial markets. In contrast, the herding theory cannot describe individual Muslim investors' behavior in making investment decisions in the real and financial sectors in East Kalimantan Province.