This study was conducted to determine the levels of job stress, as well as its association with psychosocial factors (type A behavior pattern, locus of control, and self-esteem). Self-administered questionnaires were given to 634 clerical public officers in the C Provincial Office between February 18 and Mar. 10, 2013. As a result, the job stress levels of the subjects was significantly different according to age, sex, educational level, marital status, job position, job career, satisfaction in job life, smoking, alcohol drinking, sleeping time, type A behavior pattern, locus of control, and self-esteem. Regarding the correlation of job stress and psychosocial factors, the level of job demand was negatively correlated with the internal locus of control. The decision latitude was negatively correlated with the type A behavior pattern, internal locus of control and self-esteem. Supervisor support was negatively correlated with the external locus of control. In hierarchial multiple regression analysis, the affecting factors to the job stress selected variables, such as age, subjective health status, job position, overtime work, experience of sick absence, satisfaction in work, sleeping time, leisure time, visiting out-patient department, type A behavior pattern, locus of control, and self-esteem, and the explanatory powers of these factors was 32.1%. In particular, the factors related to the psychosocial factors (type A behavior pattern, locus of control, self-esteem) were strongly related to the job stress, increasing the explanation of factors up to 15.0%.