Abe Masahiro (阿部 正弘, December 3, 1819 – August 6, 1857)[1] was the chief senior councilor (rōjū) in the Tokugawa shogunate of the Bakumatsu period at the time of the arrival of Commodore Matthew Perry on his mission to open Japan to the outside world.

Upon his father's death in 1826, his elder brother Masayasu became daimyō of Fukuyama; Abe was moved to the domain's naka-yashiki ("middle residence") in Hongō, Edo (modern-day Bunkyō, Tokyo).

This would be the only time that Abe set foot in his domain, as his career as a bureaucrat within the Tokugawa shogunate eclipsed his obligations to return to Fukuyama under the sankin-kōtai system.

One of his acts was to order the destruction of the Nichiren sect temple of Kannō-ji, whose priests had become involved in a scandal with ladies of the Ōoku under Shōgun Tokugawa Ienari.

He became rōjū shuza (老中首座, presiding senior councillor) in September 1845, after Mizuno Tadakuni lost his standing over the failure of the Tenpō Reforms.

In the meantime, he kept the shogunate abreast of foreign political developments, such as the outbreak of the First Opium War, which provided an impetus to strengthen the nation’s coastal defenses to help maintain the isolationist policies of the time.

Nevertheless, Perry, who hailed from a military family and himself had been hardened by combat in war, chose to use bluffing tactics in flagrant violation of Fillmore's wishes.

After refusing Japanese demands that he proceed to Nagasaki, which was the designated port for foreign contact, and after threatening to continue directly on to Edo, the nation’s capital and to burn it to the ground if necessary, he was allowed to land at nearby Kurihama on July 14 and to deliver his letter.

Of the remainder, 14 gave vague responses expressing concern of possible war, seven suggested making temporary concessions and two advised that they would simply go along with whatever was decided.