The Swedish Security Service is a Swedish government agency organized under the Ministry of Justice. It operates as a security agency responsible for counter-espionage, counter-terrorism, as well as the protection of dignitaries and the constitution. The Swedish Security Service is also tasked with investigating crimes against national security and terrorist crimes. Its main mission, however, is to prevent crimes, not to investigate them. Crime prevention is to a large extent based on information acquired via contacts with the regular police force, other authorities and organisations, foreign intelligence and security services, and with the use of various intelligence gathering activities, including interrogations, telephone tapping, covert listening devices, and hidden surveillance cameras.

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.