Self-efficacy for social participation (SESP) of people with mental illness was examined in urban areas of Japan and China. The subjects were 266 people (140 Japanese, 126 Chinese) with mental illness who were living in their local community. Our SESP scale (SESP27) and the Rosenberg Self-Esteem Scale, Norbeck Social Support Questionnaire (NSSQ), Sense of Coherence measure (SOC13), General Health Questionnaire (GHQ12), and a self-administered questionnaire related to living conditions were used for data collection. Data were analyzed descriptively, correlations between scales were examined, and multiple regression analysis was performed by country. The results showed that annual income was related to SESP in Japan and China. Therefore, improvement of welfare and employment support for economic independence is likely to improve SESP of people with mental illness in both countries. In addition, SESP in people with mental illness is affected by self-esteem in Japan, and coping skills such as improvement of life functions in China. Thus, SESP is affected differently by the social, cultural and institutional characteristics of each country.