The Third Koizumi Cabinet governed Japan for the final year of Junichiro Koizumi's term as prime minister, from September 2005 to September 2006, following the landslide victory of his coalition in the "postal election" of 2005.

[1] Following his re-election by the National Diet on September 21, Koizumi did not make any ministerial changes when inaugurating his third cabinet, keeping his previous team in place to focus on the re-introduction and passage of the bills to privatize Japan Post, which had formed the basis for his re-election campaign.

[2][3][4] Once this was accomplished, Koizumi conducted his final cabinet reshuffle on October 31 at the end of the Diet session.

This reshuffle promoted several potential successors including Sadakazu Tanigaki, who was reappointed as Finance Minister, Tarō Asō, who was moved to become Foreign Minister, and Shinzō Abe, who was promoted from LDP Secretary General to the post of Chief Cabinet Secretary.

[9] This gave him just one year following his re-election to conclude the reforms he had advocated during his terms of office, though he admitted in September 2005 that some would not be achieved in that time, such as constitutional revision to allow the Self-Defence Forces full military status.