Objective: Even though the number of health professionals is growing in many counties in Southeast Asia, the shortage of mental health professionals remains a challenge. The current model of professional training needs to be changed to foster cooperative and collaborative skills, through interprofessional and transprofessional education, so professionals as well as non-professional service providers and operational personnel are trained to be members of the health teams. However, training needs in each Southeast Asian country remains unknown. The present study surveyed these needs using Hennessy-Hick’s criteria and experts’ opinions. Materials and Methods: Fifteen representatives from Thailand, Cambodia, and Indonesia, mostly psychiatrists, nurses, and psychologists, attended the meeting and presented for 30 to 50 minutes on the condition of mental health services and training needs in their countries. All representatives were asked to complete an online-shared report of the adapted Hennessy-Hicks Training Analysis Questionnaires. Results: According to the Hennessy-Hick’s criteria, some teamwork tasks were required for Thailand, whereas most tasks were required for Indonesia and Cambodia. Training on special topics depended on the country’s necessity. Basic skills are needed in all ranges of mental health issues. Thailand and Indonesia expressed quite similar needs, while Thailand had identified itself as having ‘an aging society’, which ‘caring for patients with dementia and caregivers’ in their training needs were more urgent than Indonesia. Training non-psychiatric professionals, such as primary physicians and nurses, concerning mental health issues, might help to address current mental health needs in Thailand, while Cambodia was concerned about recruiting mental health professionals and focusing on providing sufficient services for the country rather than training non-professionals to deal with mental health issues. Conclusion: The training needs for mental health professionals centered on research, clinical tasks, and communication, while including nonprofessional mental health providers in training of basic skills such as communication and up-to-date technology are deemed important at the present. Keywords: Training Needs Analysis; Thailand; Cambodia; Indonesia; Mental Health