Eighty seven hostage barricade incidents that occurred in Japan from the period of 1970 to 2000 were examined to analyse factors influencing hostage takers' decisions to surrender. Though previous studies on hostage takings focused on criminals' psychological and/or psychiatrical characteristics, the current analyses revealed that surrounding factors at the time of hostage takings effected hostage takers' decision making. The x² test and the logistic regression analysis showed that injuries/death of hostages' negatively influenced hostage takers' surrender, while the 'conversation between hostages and hostage takers', 'hostage takers' demands of media reports', and 'barricading within buildings' led to their surrender. Based on these findings, psychological processes of hostage takers' decision making were discussed, together with those of police officers.