Miki became prime minister in 1974 upon the resignation of Kakuei Tanaka, who had faced allegations of corruption, but his attempts to pass anti-monopoly legislation and political funding laws failed amid opposition from within his party.

Aside from farming, his father traded fertilizers, sake, rice and general goods, though he was not a wealthy farmer (gōnō) or from a family of pedigree (kyūke).

[3] In the earlier post-war period, Miki led the centrist National Cooperative Party in the 1947 and 1949 general elections, to limited success.

As the head of an LDP faction, Miki held cabinet posts in the administrations of Ichirō Hatoyama, Nobusuke Kishi, Hayato Ikeda, and Eisaku Satō.

[7] As punishment for taking part in the anti-Kishi rebellion, Miki was initially excluded from the cabinet of Kishi's successor Hayato Ikeda.

However by the following year, Ikeda had cemented his power enough to overcome the objections of the Kishi faction and bring Miki back into the cabinet as Head of the Science and Technology Agency.

[9] In matters of regional foreign policy, Miki was an early advocate of Asia-Pacific economic cooperation and, in 1968, he said that "'it would be an act of suicide on our part to create an exclusive and closed trading bloc in the Pacific area.

The attractiveness of Miki to the LDP bosses was chiefly due to his personal integrity, and his weak power base from his small faction.

[citation needed] While Miki was at the funeral of ex-PM Eisaku Sato in 1975, he was assaulted by a right-wing extremist named Hiroyoshi Fudeyasu, the secretary-general of the Greater Japan Patriotic Party[12] with foreign dignitaries nearby.

[12] In a 1976 Diet session, Miki reaffirmed a past order of Prime Minister Satō's cabinet dating back to 1967 in which the percent of the national GDP allocated towards defense spending was frozen so as to not exceed 1%.

In any event, Miki also pushed the Diet to fully ratify the Treaty on the Non-Proliferation of Nuclear Weapons,[17] and he also worked to further strengthen previous policies set in motion by Prime Minister Satō which virtually committed Japan to not engage in the export of arms to any country.

[18] After being elected, Miki attempted to reform the LDP, relentlessly investigating the Lockheed bribery scandals and refusing to halt the criminal prosecutions being made against his predecessor.

[24] In Hong Kong, the name "Takeo Miki" (三木武夫) is sometimes used to describe actors or actresses with wooden or no emotional expressions during movies or TV dramas.