This core document establishes international principles and practices for medical device cybersecurity, covering the complete device lifecycle. It specifies requirements for security by design, vulnerability management, and incident response frameworks. Manufacturers should integrate cybersecurity considerations throughout product development, maintenance, and end-of-life phases. The document serves as the common foundation referenced in Japan's Basic Principles for Conformity Assessment of Medical Devices (Article 12, Paragraph 3), FDA 2023 final cybersecurity guidance, and EU MDCG cybersecurity guidance. Japanese regulatory authorities directly reference this document in official notifications, making it essential for regulatory compliance in multiple jurisdictions.