This research aims: (1) to produce a character-based reflective picture storybook to improve social self-concept and (2) to determine the effectiveness of the character-based reflective picture storybook in improving the social self-concept. This research was R & D developed by Borg & Gall (1983). The subjects were the fifth grade students of elementary schools in Yogyakarta, Indonesia. The data collection techniques were interview, observation, scale, and questionnaire. Data was analyzed by a paired t-test and independent t-test at 0.05 significance level. The result of the research shows that: (1) the character-based reflective picture storybook has passed the criteria of feasibility to improve student’s social self concept based on expert validation result, teacher response scale, and student response scale with very good criteria; (2) the character-based reflective picture storybook is effective to improve the social self-concept based on the t-test result with significance level < 0.05, that is 0.000. Through pictorial stories and reflection activities developed in the character-based reflective picture storybook, elementary students can internalize the values of characters in a more fun way, acquire knowledge in accordance with the curriculum, and add insight into how to interact with others in the surrounding environment.