Japan's intelligence system is complex, huge and diverse.

The Japanese intelligence system refers to the fact that in Japan, the intelligence collection work is scattered among six or seven departments, including some ministries and agencies of the Cabinet, the Cabinet Office of Japan and the Self-Defense Forces. Among all intelligence departments, the key roles are the Intelligence Headquarters of Japan's Defense Agency, the Cabinet Intelligence Research Office directly under the command of the Prime Minister, and the public security investigation agency mainly responsible for preventing domestic subversion.

After the war, the intelligence system established in Japan was very large and had many branches. The main intelligence agencies were: the Intelligence Investigation Office of the Cabinet and the Intelligence Investigation Office of the Ministry of Foreign Affairs, a military reconnaissance agency; Intelligence and communication bureau of the police department; Ministry of Public Security of Metropolitan Police Department; Department of Public Security Investigation, Ministry of Justice; Military anti-reconnaissance organs; Immigration department; Coast guard.

Cabinet Intelligence Investigation Office: This is the leading national intelligence agency in Japan, whose duty is to collect information necessary for cabinet members to make decisions, especially political decisions. Military reconnaissance agencies: Japanese military reconnaissance agencies still regard Russia, China and North Korea as the primary reconnaissance targets. In order to obtain information, the agency used various reconnaissance means, including spy reconnaissance, radio technology reconnaissance, radio electronic reconnaissance and space reconnaissance.

The Intelligence and Communication Bureau of the Police Department and the Ministry of Public Security of the Police Department: One of the tasks of the intelligence agencies under the Police Department is to use the police's anti-reconnaissance means to safeguard national security. Coast Guard: Japan has one of the longest coastlines in the world. In addition to defending the coastal areas, the Coast Guard also conducts maritime reconnaissance, monitors fishing and hunting activities within 2 nautical miles, and participates in maritime rescue work.

Japan's intelligence system is very scattered due to many institutions and insufficient strength of various departments.