This Act is specifically formulated to promote the mental health of the population, prevent and treat mental illnesses, protect patients’ rights and interests, support and assist patients living in community.

The competent authorities mentioned in this Act are Department of Health, Executive Yuan at the central level, the municipality governments at the municipality level, and county (city) governments at the county (city) level.

The terms used in this Act are defined as follow:
1. Mental illness: the illness with abnormal presentations in mental status such as thoughts, emotions, perception, cognition and behaviors, which cause impairment in the function to adapt to living and need medical treatment and care; its range includes psychosis, neurosis, alcohol addiction, drug addiction, and other mental illnesses recognized by the central competent authority, but not antisocial personality disorder.
2. Specialist Physician: the psychiatric specialist passing the selection and review by the central competent authority pursuant to the Physicians Act.
3. Patient: the person suffering from mental illness.
4. Severe Patient: the patient who is diagnosed and confirmed by a psychiatric specialist to present queer thoughts and odd behavior detached from reality and as a result to be incapable of managing their own affairs.
5. Community Mental Health Rehabilitation: for the purpose of assisting patients to adapt to social life gradually, the rehabilitative treatment offered to patients in community as regards work ability, work attitude, psychological reconstruction, social skills, and ability to manage daily life, etc.
6. Community Treatment: for the purpose of preventing the deterioration of a severe patient’s illness, the modalities of treatment in community that adopt home care, community mental rehabilitation, outpatient treatment, etc.