After graduating in 1939, he joined Chugai Shōgyō Shimpo (later renamed Nihon Keizai Shimbun) and was appointed as its chief correspondent in Shanghai.

He joined the Liberal Democratic Party (LDP) in 1955, serving as Chief Cabinet Secretary under two prime ministers, Tanzan Ishibashi and Nobusuke Kishi, from 23 December 1956 to 10 July 1957.

[1][2] Ishida's article shocked the LDP, but was hailed as perceptive, and stimulated the party to make a number of reforms, including to changing its policies to increase its appeal among urban workers.

In 1982 Stanislav Levchenko, a KGB Major who had defected to the United States in 1979, testified before the U.S. Congress that Ishida was an agent for the Soviet Union, codenamed "HOOVER".

In response to Levchenko's revelations, the CIA and the Japanese police launched an investigation, and Ishida abruptly left politics in November 1983.