The purpose of this study was to examine what kind of manner people have towards surrogate decision making. Thr ee groups of patients in capable of self-decision were simiated. Subjects were asked how they would make a decision if the patient was their family member. The three groups of patients consisted of :(a) people with mental retardation, (b) people with persistent consciousness disturbance,and (c) newborn infants with a serious disorder. Questionnaires concerning surrogate decision making were performed on 473 undergraduate students. in all three situations, ""treat actively""and ""0nly terminal care"" held the majority. The percentage of the subjects who selected ""death with dignity"" and ""euthanasia"" was around 10-15%. When self had to make a decision about himself/herself, ""death with dignity"" received the most social consensus. On the other hand, when the decision was about a family member, most people wanted their family members to live slightly longer. In all, it is suggested that surrogate decision making of a family member is difficult.