The court ruled that Hashimoto and other members of the cult sprayed sarin gas in the central Japanese city of Matsumoto in June 1994, killing seven residents under the instruction of Aum guru Shoko Asahara.
“It was an organised, cruel crime,” presiding judge Osamu Tsuno said as he confirmed Hashimoto’s sentence.
“He bears grave criminal responsibility,” he said, as quoted by Jiji Press.
The court also ruled that Hashimoto killed an anti-sect lawyer and his wife and their baby in 1989.
Hashimoto will now be transferred to death row to await hanging, except in the unlikely event that the Supreme Court accepts a special appeal arguing that his sentence is unconstitutional.
The 1994 incident was largely seen as a rehearsal for the attack a year later on Tokyo subway trains that left another 12 people dead and thousands injured.