Masami Tsuchiya (土谷正実 Tsuchiya Masami) is a former senior Aum Shinrikyo scientist who played a leading role in the production of lethal chemicals including sarin.

Tsuchiya was sentenced to death by a Japanese court on January 30, 2004 for his role in the Sarin gas attack on the Tokyo subway in 1995 which resulted in up to 6000 injuries and several deaths.

Tsuchiya plans to appeal the ruling; he pleaded innocent to most of the 6 charges brought against him, claiming that the sarin AUM members used in a previous sarin attack in the city of Matsumoto, and later on the Tokyo subway system, was not produced by the group.

Tsuchiya is the 11th member of AUM who has been sentenced to death over the group's fatal terror attacks. The ruling on AUM founder Shoko Asahara, whose real name is Chizuo Matsumoto, is set for February 27, 2004. He was sentenced to death, but is also appealing the verdict.