Objective: To clarify the multiple stakeholders' perspectives on the research phase and themes in patient and public involvement（PPI）in community mental health and welfare research.

Methods: Semi-structured focus group interviews were conducted with 37 participants who included individuals with mental disorders and family members, practitioners, government staff, and researchers. In the interviews, the participants were asked about two points: which phase of PPI research they would like to or be able to collaborate, and whether changes their willingness to collaborate depending on the research themes and methods. Qualitative content analysis was performed to categorize the qualitative data.

Results and Discussion: Two domains were related to the research phase: ［Possibility of PPI implementation by research phase］and［Significance of PPI implementation in each research phase］. Positive views on collaboration in all the research phases were found. It was further revealed that flexibility is desirable, and a perception of the significance and the sense of challenge involved in participating each research phase of PPI research by persons with mental disorders and family members. Further, two domains, namely,［Feasibility of PPI by research themes］ and ［Research themes for which PPI-based research is effective or expected to be implemented］were generated in accordance with concrete opinions thereof. The issues that should be resolved through the accumulation of best practices and consideration of solution strategies were presented in relation to the dissemination of PPI in community mental health and welfare research.