It is said that when driver faced to yellow signals, accidents are caused by driver's hesitation for deciding to pass the intersections or to stop at the stop-line. The purpose of this study is to find out factors influencing on driver behaviors using a driving simulator; distance to the stop-line, existence of a following vehicle, and understanding of the rule of yellow signal. We also analyzed the relationship between driver's own awareness and their behavior, on the basis of interviews to participants.