Ishihara, 80, told reporters at a news conference in Tokyo that he wanted to return to parliament and said he would run in the next election for the House of Representatives, Japan's lower house.
Ishihara has served as Tokyo governor since 1999, following a quarter of a century in parliament. Known as a fierce nationalist and co-author of the 1989 book "The Japan That Can Say No," he has pushed for Japan to rewrite its pacifist constitution and advocated acquiring nuclear weapons.
Last spring, he announced his intention to have his metropolitan government purchase three islands -– known as the Senkakus in Japan and Diaoyu in China -– from a Japanese family that has administered them in recent decades. China claims the islands as its territory, and some believe the nearby seabed holds significant energy reserves.
Japan's national government, fearing that Ishihara might attempt to build structures on the outcroppings or otherwise develop them and try to change the status quo, announced in September that it would buy the islands. That "nationalization" set off a serious diplomatic row with China and sparked violent protests in scores of Chinese cities that have seriously damaged economic ties with Japan.
After many years as a member of the long-ruling Liberal Democratic Party, Ishihara became an independent prior to running for governor of Tokyo. He indicated Thursday that he may join forces with a relatively new political group, the Japan Restoration Party, headed by the mayor of Osaka.
Prime Minister Yoshihiko Noda of the Democratic Party of Japan is facing dismal public poll numbers and increasing opposition within parliament. Although he is not required to call elections until next summer, he has promised to do so "soon."
The DPJ, which came to power in 2009, is facing a fresh challenge from the Liberal Democrats, who recently elected former Prime Minister Shinzo Abe as their head.
Like Ishihara, Abe is seen as a hawk who has called for Japan to take a firm line with its neighbors and tighten its alliance with the United States. He has also pushed to revise the nation's constitution.
-- Julie Makinen
Photo: Tokyo Gov. Shintaro Ishihara on Thursday announces his resignation from his post at the Tokyo city hall. Credit: Yoshikazu Tsuno / Agence France-Presse/Getty Images