Ishibashi succeeded Hatoyama as prime minister in 1956, simultaneously serving as director of the Defense Agency, but resigned soon after due to ill health.

Ishibashi was born in the Shibanihonenoki district of Azabu ward, Tokyo in 1884, the eldest son of Sugita Tansei (1856–1931),[1] a Nichiren Buddhist priest and the 81st head of Kuon-ji temple in Yamanashi prefecture.

After he finished military service, he joined the staff of the Tōyō Keizai Shimpo ("Eastern Economic Journal"), later becoming its editor-in-chief and finally company president in 1941.

In this regard, he also promoted a feminist perspective, advocating comprehensive "legal, political, educational, and economic" equality for women so that they could better thrive in the competitive modern society, in contrast to the stratified conditions of feudal life.

[6] After World War II Ishibashi received an offer from the Japan Socialist Party to run for the National Diet as their candidate.

[12] In the postwar period, a practice had developed whereby each prime minister would attempt to achieve a major foreign policy objective.

[14] Ishibashi also signaled that he would endeavor to take a cooperative approach to the political opposition, resulting in high public approval ratings.

When Kishi had opposition lawmakers physically removed from the Diet by police and rammed the new treaty through on May 19, 1960, Ishibashi was one of several LDP faction bosses who boycotted the vote in protest.