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Class IV — Specially Controlled Medical Devices (Highest Risk)

Class IV is the highest-risk category of medical device under Japan's PMD Act classification system. All Class IV devices must use the Shonin (full approval) pathway — there is no Ninsho option.

Characteristics​

Class IV devices:

  • Are implanted in the human body for more than 30 days, OR
  • Contact the central nervous system, cardiovascular system, or vital organs and are life-sustaining/life-supporting, OR
  • Are IVDs used for blood transfusion compatibility or infectious disease screening (e.g. HIV)
  • If defective, pose a risk of death or serious irreversible injury

Examples of Class IV devices​

Drug-eluting stents, pacemakers, ICDs (implantable cardioverter defibrillators), artificial heart valves, cochlear implants, HIV diagnostic IVDs, SARS-CoV-2 IVDs used for blood screening, total hip and knee replacements with Class IV designation.

Regulatory pathway — Shonin only​

Class IV devices always require full Shonin approval. Key features:

  • Full PMDA scientific review with typically 12–24+ (standard review may be 12–18 months; priority review may be shorter; complex cases may exceed 24 months) month standard review timelines
  • Comprehensive clinical evidence package required — foreign clinical data may be accepted with appropriate justification
  • QMS inspection of all manufacturing sites (both domestic and foreign) as part of the approval process
  • Conditions on approval are common — e.g. requirements for post-market registry studies

Re-examination period​

Class IV devices are subject to a re-examination period of typically 4–7 years (varies by device type), during which extensive post-market use-results data must be collected and submitted to MHLW.

For example, many Class IV cardiovascular devices require enrolment in a post-market surveillance registry (e.g. for long-term safety monitoring), and some devices require mandatory physician training before implantation.