Purpose: This study aimed to identify relationships among knowledge and skills about suicide prevention, attitudes toward suicide, and burnout of suicide prevention work of nurses at mental health welfare centers. Methods: An explanatory sequential mixed-method research was conducted. For the quantitative study, the subjects (nurses) were 133 nurses executing suicide prevention work. The data were analyzed using the SPSS 25.0 program. For the qualitative research, 13 nurses with high burnout scores were interviewed. The data were analyzed using theme analysis method. Results: Quantitative results showed the average burnout of suicide prevention work was 54.62 ± 12.51. The burnout of suicide prevention work had significant correlations with attitudes toward suicide (r = .30, p < .001) and suicide prevention skills (r = - .18, p = .037). Qualitative results showed six themes related to burnout of suicide prevention work. They were ‘feeling a lack of confidence in one’s suicide counselling skills’, ‘feeling of the limits of one’s ability to cope with a suicide crisis’, ‘feeling regret for not being able to help the clients’, ‘being over-empathetic to the clients’, ‘Not being able to understand the clients because the subjects (nurses) opposes committing suicide’, and ‘thinking that the suicidal thoughts of suicide attempters do not improve’. Conclusion: To reduce burnout of nurses’ suicide prevention work at mental health welfare centers, there is a need to develop an educational program considering nurses' attitudes toward suicide and one to enhance their confidence in suicide prevention skills.