The purpose of this study was to evaluate attitudes toward mental illness in nursing students after clinical practice of psychiatric nursing. A quasi-experimental study with one group pretest-posttest design. Data were collected by questionnaires from 77 nursing students from T university, Busan. The clinical practice of psychiatric nursing was given 5 days, total 45 hours in psychiatric hospital located in Busan. The data were analyzed using descriptive statistics and t-tests. There were not significant differences in self-acceptance, communication competence. In the areas of the attitudes toward mental illness, scores of authoritarianism (t=16.81, p<.001), Benevolence (t=14.18, p<.001), social restrictiveness (t=9.67, p<.001) and community mental health concept(t=12.08, p<.001) were significantly different before and after the clinical practice of psychiatric nursing. In the all areas of the attitudes toward mental illness, scores were decreased after the clinical practice. In the benevolence and community mental health concept, the positive attitudes toward mental illness were increased. The results indicate that psychiatric clinical practice provides positive effects on benevolence and community mental health concept in the areas of the attitudes toward mental illness.