AIM: Various factors may influence on development of identity sense. The aim of this study is to investigate effects of various factors including age, number of siblings, birth order, level of income, parents' level of education, family types and living in urban or rural on development of identity sense in male adolescents. METOD: The sample consisted of 537 male adolescents from a health technician vocational high school. Participants were given a sociodemographic questionnaire and the Sense of Identity Assessment Form (SIAF). RESULTS: Identity confusion was found in 15.3% of the sample. The mean score of SIAF reached peak level at 17 years old and then gradually decreased. The mean SIAF score of rural-based adolescents was significantly higher when compared with that of urban-based adolescents (p<0.05). The adolescents living in low income families showed significantly higher SIAF scores (p<0.05). The sons of fathers with low education (below 8 yrs) had higher mean SIAF score (p<0.05). CONCLUSION: This study suggests that male adolescents who live in low income families and rural, and have father with low level of education are more likely to have identity confusion.