The Ministry of State Security is the principal civilian intelligence, security and secret police agency of the People's Republic of China, responsible for foreign intelligence, counterintelligence, and the political security of the Chinese Communist Party (CCP). One of the largest and most secretive intelligence organizations in the world, it is headquartered in the Haidian District of Beijing, with powerful semi-autonomous branches at the provincial, city, municipality and township levels throughout China.

A security agency is a governmental organization that conducts intelligence activities for the internal security of a nation. They are the domestic cousins of foreign intelligence agencies, and typically conduct counterintelligence to thwart other countries' foreign intelligence efforts.