The Tokyo subway sarin attack (, Chikatetsu Sarin Jiken, "Subway Sarin Incident") was an act of domestic terrorism perpetrated on 20 March 1995, in Tokyo, Japan, by members of the cult movement Aum Shinrikyo. In five coordinated attacks, the perpetrators released sarin on three lines of the Tokyo Metro (then Teito Rapid Transit Authority) during rush hour, killing 14 people, severely injuring 50 (some of whom later died), and causing temporary vision problems for nearly 1,000 others. The attack was directed against trains passing through Kasumigaseki and Nagatach, where the Diet (Japanese parliament) is headquartered in Tokyo.The group, led by Shoko Asahara, had already carried out several assassinations and terrorist attacks using sarin, including the Matsumoto sarin attack nine months earlier. They had also produced several other nerve agents, including VX, and attempted to produce botulinum toxin and had perpetrated several failed acts of bioterrorism. Asahara had been made aware of a police raid scheduled for March 22 and had planned the Tokyo subway attack in order to hinder police investigations into the cult and perhaps spark the apocalypse they believed in. The leader also wanted to start a Third World War.

In the raid following the attack, police arrested many senior members of the cult. Police activity continued throughout the summer, and over 200 members were arrested, including Asahara. Thirteen of the senior Aum management, including Asahara himself, were sentenced to death and later executed; many others were given prison sentences up to life. The attack remains the deadliest terrorist incident in Japan as defined by modern standards.

Shoko Asahara (麻原 彰晃, Asahara Shōkō, March 2, 1955 – July 6, 2018), born Chizuo Matsumoto (松本 智津夫, Matsumoto Chizuo), was the founder and leader of the Japanese doomsday cult known as Aum Shinrikyo. He was convicted of masterminding the deadly 1995 sarin gas attack on the Tokyo subway, and was also involved in several other crimes. Asahara was sentenced to death in 2004, and his final appeal failed in 2011. In May 2012, his execution was postponed due to further arrests of Aum members. He was ultimately executed on July 6, 2018.