[영문]We examined the effect of life satisfaction on survival over 10 years among 80-year-old and older same-sex twins of whom 320 individuals responded to the Life Satisfaction Index Z questionnaire in connection with the OCTO-Twin study. We treated participants as individuals in semiparametric Cox regression mixed-effects models (frailty) by adjusting the similarity of mortality risk within twin pairs by modeling it as a random variable. An exploratory factor analysis yielded three factors: Zest and Mood represented satisfaction with present life and Congruence represented satisfaction with past life. Those in the lowest quartile of factors of satisfaction with present life had an almost twofold risk for mortality compared with those in the highest quartile, even after adjustment for multiple confounders. Satisfaction with past life satisfaction showed no association with mortality.