This research could help prevent suicide of teenagers, is to know the RFL-A, 'The Reason for Living Inventory for Adolescents' and to validate the RFL-A by adapting it. The RFL-A refine the questions, performing work to verify usability of question and determined the questions suitable for purpose of this research through the discussion with experts in each filed. After examining reaction of 7 graduate students majoring in counseling psychology to questions about RFL-A, the final questions were selected. For this research, the following subjects for inquiry were chosen. First, is the factor structure of RFL-A same as the original one's ? Second, how the relation between RFL-A and other criteria (suicidal behavior, despair, optimism, social desirability) is? This research subjects are middle and high school students or age from 13 to 19 living live in Seoul, selected for sample group among teenagers who were counseled or treated from K counseling center or S hospital. There were 560 questionnaires returned centrally from 5 schools, 3 counseling center or hospitals, item analysis, reliability analysis, confirmatory factor analysis and correlation analysis were conducted by using the statistical program, SPSS 18.0 and AMOS 18.0 for totally 460 questionnaires after excluded 100 questionnaires, which were judged as lack sincerity. The results from this research are as follows. First, as a result from confirmatory factor analysis of the RFL-A, the measuring models of RFL-A could be said that they were designed satisfyingly for research data. Second, to know if subscale of RFL-A is valid, the criterion related validity was searched, conducting the correlation analysis of sub-factors in other relevant criteria, the subscale of RFL-A, family alliance was in negative correlation with despair and suicide behavior among sub-factors but in highly positive relation with optimism to the future. And, the subscale of RFL-A, self-acception showed the negative correlation severly but showed highly positive correlation with optimism. The subscale of RFL-A, peer acceptance and support had negative correlation with despair but highly positive correlation with optimism. And also, the subscale of RFL-A, optimism to future showed very high degree of negative correlation with despair but showed very high degree of positive correlation with optimism. These results verified that the subscale of RFL-A is closely connected with despair. To have the result of this research for subscale of RFL-A obtain more empirical effect, the follow-up researches expanded the sampling model of research subject must be constantly continued.