This study was conducted to explore the resilience change of upper grade elementary school students who participated in the thanks journal writing activities in the beginning of school year. Resilience was known as the very important psychological factor to overcome environmental threats and stress and difficulties accompanied in the developmental process. This study selected two 5th grade classes in the S city, composed of 47 students dividing one class as an experimental group(23 students) and the other as a control group(24 students) and assigned a control group to write thanks journal on a daily basis for 4 weeks. For the thanks journal writing, three free topics could be selected without any limits and students were also asked to write personal reflections on their thanks journal writing activity. In order to analyze the effects of thanks journal writing, resilience measurement test was assigned to both groups before and after the activity and mean score changes of resilience were compared between two groups with independent sample t-tests. In addition to comparison of resilience mean score changes of both groups, this study conducted content analysis of students’ thanks journals and personal reflections in order to find out the changes of students’ attitude and thoughts. Major results were as follows. First, the experimental group showed significant increases in resilience scores overall and its sub factors including self regulation, positivity, and interpersonal competence as well. Second, content analysis of thanks journal showed that students wrote the thanks contents composed of school and out-of school life. In terms of school life, study, daily life and relationships were revealed and in terms of out-of school life, survival, daily life and relations were included. Third, the analysis of the students’ reflections revealed self-reflection on their own emotions, efforts for self changes, transition to positive perspective, getting awareness on importance of everyday life and building better relationships. Based on such findings, this study suggested that thanks journal writing activity contribute to improving resilience and helping students’ school adjustment in the new school period, and further could be applied to more school settings.