The purpose of this research is to experimentally clarify the influence both of mar- ket factors related to market conditions and of investors’ individual factors related to cognitive tendency on their investment behavior; for this purpose, we conducted an ex- periment using an experimental market in which participants were asked to buy and sell stocks whose prices were controlled. Specifically, we analyzed generalized linear mod- els where each of three behavioral indicators related to investment (the ratio of trend following trading, the extent to which a participant took risks, and disposition effect) was a response variable and both market factors (market trend and volatility) and in- vestors’ individual factors (risk attitude and degree of proficiency) were explanatory variables, so that we could identify whether or not the explanatory variables explained each response variable. Five professional traders and 11 personal investors participated in this experiment. As a result, the following three things were clarified: First, it was affected not by market factors but by their risk attitude whether they followed market trends or not; second, the extent to which they took risks was affected both by market factors and by their degrees of proficiency; finally, disposition effect was affected only by degree of proficiency, which meant that professional traders could avoid disposition effect.