It is encouraging that the Mental Health Treatment Order has been implemented as part of the punishment for offenders with mental illness and the reinforcement of supervision, allowing for therapeutic access to offenders with mental disorders or drinking and drug problems. However, it is often difficult to deal with offenders who are subject to community supervision without Mental Health Treatment Order because mental health problems often reveal. Even though the law-enforcement agency must take a therapeutic approach to offenders with mental disorders along supervision on criminal conduct, it is difficult to supervise them effectively due to the absence of legal grounds, heavy duties and insufficient resources. Based on this point, this study conducted a questionnaire and interview with 16 probation officers about their experience in guiding probationers with mental disorder to identify the difficulties of supervising them on site and to suggest solutions to them. As a result of reviewing the responses of probation officers, the risk of lack of understanding about legal sanctions, lack of human and material resources to solve mental problems, and awareness of the families of probationers with mental disorder, lack of legal basis to enforce hospitalization despite the high risk of self-harm and re-offending caused difficulties. By proposing practical techniques to address these challenges in field practice, the recurrence and recidivism of the probationers with mental disorder were to effectively mitigate while enhancing the professionalism and efficiency of probation officers.