This study explored how various professionals and care workers perceived resident-to-resident abuse (RRA) in nursing homes for older adults. We conducted in-depth interviews with sixteen professionals and care workers. Specifically, they were nursing staff, social workers, care assistants, lawyers, and professors who had researched elder mistreatment. The three main dimensions, ten themes and 25 categories were deducted. The first dimension of “perpetrators and victims of RRA” included two themes, “between residents” and “unclarity between perpetrators and victims.” The second dimension of “various negative interaction and occurrence frequencies” included “emotional, physical, sexual, and financial interaction” and “various occurrence frequencies.” The final dimension of “causes and risk factors from multi-system perspectives” contained four themes, “resident factors,” “relational factors,” “worker and organizational factors,” “family factors”, and “institutional and social factors.” Based on the findings, we discussed the dynamic process of RRA, the education of care workers and residents, the need to change regulation-oriented penalty systems, policy changes targeted at person-centered care, and making partnerships with the family of residents.