The Philippine Secretary of National Defense is the head of the Philippine Department of National Defense and a member of the President's Cabinet.

The Department of National Defense is the executive department of the Philippine government responsible for guarding against external and internal threats to peace and security in the country. The Department of National Defense exercises executive supervision over the Armed Forces of the Philippines (AFP), the Office of Civil Defense (OCD), the Philippine Veterans Affairs Office (PVAO), the National Defense College of the Philippines (NDCP), the Government Arsenal (GA), and Veterans Memorial Medical Center (VMMC). It is also responsible for disaster preparation and management in the country.