July 3 (Bloomberg) -- Japanese Defense Minister Fumio Kyuma quit after a public outcry over his comments suggesting the U.S. atomic bombings of Hiroshima and Nagasaki in 1945 were justified because they helped end World War II.

``I must take responsibility,'' Kyuma said in nationally broadcast remarks. ``The Prime Minister said `it is regrettable, but I accept.''' National security adviser Yuriko Koike will replace him, becoming Japan's first female defense minister.

The resignation adds to Prime Minister Shinzo Abe's woes ahead of parliamentary elections at the end of the month. Abe, who is trying to reverse his plunging approval ratings amid a scandal involving the loss of millions of pension records, yesterday reprimanded Kyuma for his remarks while saying he wanted his defense minister to stay on.

``Resignation is the most serious way to take responsibility as a politician,'' Abe told reporters in Tokyo at a regular press briefing. ``I respect his decision.''

Kyuma, who earlier today said he wouldn't step down for his June 30 comments that the nuclear attack ``brought the war to an end'' and ``couldn't be helped,'' was born in Nagasaki and represents it in the Diet's lower house. ``My remarks caused trouble to the people of Nagasaki,'' he said.

The U.S. dropped an atomic bomb on Hiroshima on Aug. 6, 1945, killing an estimated 90,000 people. Nagasaki was bombed three days later, killing an estimated 70,000 people. Both bombs left tens of thousands more injured and suffering from radiation poisoning. Japan surrendered on Aug. 15.

Damaging Remarks

``His remarks have already damaged Abe's administration, but he tried to limit the impact,'' said Tomoaki Iwai, a professor of political science at Nihon University in Tokyo. ``Abe should have taken more severe measures against Kyuma from the beginning, but he tried to support him.''

Half of the upper house's 242 seats are up for grabs in the July 29 elections. Abe's Liberal Democratic Party and partner New Komeito need to win 64 seats to keep majority control. The LDP controls the more powerful lower house.

``He decided to resign because he expected a negative impact on the elections,'' said Yukio Hatoyama, secretary-general of the main opposition Democratic Party of Japan. ``He should have quit right after making such comments.''

Kyuma, at a later press conference, said his comments have already been a ``minus'' for Abe that may ``get in the way'' of the election. Abe declined to comment on the possible impact of the resignation on the July elections.

Koike will work to restore confidence in Japan's defense policy, Chief Cabinet Secretary Yasuhisa Shiozaki said at a regular press conference. A graduate of Cairo University fluent in Arabic and English, Koike is a former television journalist and member of the lower house. There is no plan to replace her as security adviser, Shiozaki said.

`Won't Make Gaffes'

``Abe chose her to help get through the upper house elections,'' Iwai said. ``She's in charge of security and as a former anchorwoman good at speaking. She won't make gaffes.''

Koike, speaking to reporters at Abe's official residence in Tokyo, said she will work hard to protect Japan.

Japan annually holds memorial services for the victims of the atomic bombings and every year submits a United Nations resolution calling for the elimination of nuclear weapons. The country forbids the development or possession of such weapons on its soil.

Abe's popularity has plunged after a government agency said it can't identify 50 million pension records, resulting in possibly millions of dollars in unpaid benefits, and following the suicide of his agriculture minister in May. His approval rating fell to 28 percent, the lowest since taking office in September, the Asahi newspaper said yesterday.

To contact the reporter on this story: Sachiko Sakamaki in Tokyo at Or ssakamaki1@bloomberg.net

Last Updated: July 3, 2007 06:42 EDT