To include people with disabilities as equal citizens, CRPD (Convention on the Rights of Persons with Disabilities) promotes direct or supported decision-making by people with disabilities. However, involuntary psychiatry admission is considered in many countries to be necessary for people with psychosocial disabilities. To overcome the tension and implement CRPD, it is essential to understand the experiences and concerns of service users, family members, and medical professionals in each country. To understand the process and the factors that make psychiatrists decide involuntary psychiatric admission in Japan, and explore their attitudes toward direct or supported decision-making by people with psychosocial disabilities. Psychiatrists who had authorized involuntary admission and who were in charge of the service users were recruited at hospitals in Japan. The interviews were individual, peer to peer, and semi-structured. The interviews were audio-recorded, transcribed verbatim, and the analysis followed reflexive thematic analysis using NVIVO 12. Six psychiatrists (five designated psychiatrists and one psychiatric resident) participated in the study at two hospitals in urban Japan. The study found that the psychiatrists assessed symptoms, behaviors, and perceptions of the service users together with supports and wishes of their families. The psychiatrists decided on involuntary admission when they saw self-harm or violence, weak insights and judgment abilities, family's wishes, or when they wanted to avoid the service users leaving the hospital with incomplete treatment. The psychiatrists felt that the service users would not understand any explanations, which made their communications minimal. The psychiatrists thought it was hard to imagine a system other than the current involuntary admission mechanism. If it was to change, they felt the essential things were to avoid abuse, clarify who is responsible, make plans medically valid and feasible, and assess and plan through everyday life, not just in crisis. During a crisis, the psychiatrists were most careful about complying with the Mental Health Act and responded to the family's wish. The psychiatrists justified involuntary admission as they believed that people in a psychiatric crisis cannot decide or understand and need protection. Related protocols, laws, and expectations from family members shapes the values and practices of psychiatrists in Japan. The paper concludes with several recommendations to regard people with psychosocial disabilities as equal citizens, and promoting the aim of reducing or ending involuntary admission.