The ultra-leftist group, which sought to overthrow the Japanese government and had strong pro-Palestinian ties, is also widely believed to have been behind a 1972 attack on an Israeli airport that killed almost 30 people.
“I have hurt innocent people I did not know, by putting our struggles first,” said Shigenobu, 76, surrounded by family, media and fans holding banners, the Associated Press reported.
“Although those were different times, I would like to take this opportunity to apologize deeply,” she added.
Shigenobu wore a black-and-white Palestinian kaffiyeh scarf draped over her shoulder as she left a prison facility in Akishima, Tokyo.
Shigenobu was convicted of masterminding a siege at the French embassy in The Hague, the Netherlands, in 1974, which saw scores of diplomats taken hostage. After evading capture for decades, she was arrested in Osaka in 2000, and later dissolved the group.
Several members of the Japanese Red Army remain in hiding in the Middle East and elsewhere and are wanted by authorities, according to Japanese media.