The purpose of the study was to examine effects of runaway adolescents' self-disclosure about traumatic experience on negative emotional experience and intrusion. 46 runaway adolescences divided into two conditions. In experimental condition, participants were asked to disclosure innermost feeling and thought about their own traumatic experience for twenty minutes with three days. In control condition, participants were asked to write down about their recent daily schedules. To check the effects of self-disclosure, negative emotional experience and intrusive thinking and emotion measured three-times, before the writing, right after the writing and one week afterward the writing. Results of the study showed that writing about traumatic experience decreased negative emotional experience. And it's effects was much larger at the one week afterward than that of the right after the writing. Intrusive thinking and emotion decreased to marginal level. In contents analysis using by the K-LIWC, it was suggested that effects of the self-disclosure was mediated by the cognitive understanding of traumatic events. Results of the study were discussed in relation with previous and future studies.