TOKYO (Reuters) - Canon Inc (>> CANON INC.) has appointed its first outside directors, ending years of high-profile resistance to opening up its boardroom as pressure mounts on Japan's big companies to improve governance and better manage risks.

The camera maker's long-serving chief executive Fujio Mitarai, who headed Japan's powerful Keidanren business lobby from 2006 to 2010, had argued that only insiders could understand the company well enough to serve effectively on its board.

Canon's surprise move follows similar shifts at Japanese bellwethers such as Toyota Motor Corp (>> Toyota Motor Corp) and Hitachi Ltd (>> Hitachi, Ltd.) as globalization helps to prise open their decision-making structures to the outside world.

Canon said on Wednesday its board would be joined by Kunitaro Saida, a lawyer who has served as chief prosecutor in Osaka, and Haruhiko Kato, a former commissioner of Japan's National Tax Agency who became one of Toyota's first independent board members last June.

"Mitarai was the most powerful, most outspoken opponent to the concept of outside directors," said Nicholas Benes, a corporate governance expert and representative director of The Board Director Training Institute of Japan.

"This is a really interesting development which in a way is really good for corporate governance in Japan."

A Canon spokesman said the company had not opposed having independent directors but had been unable to find people with suitable credentials.

"We haven't had any scandals or anything that would increase pressure on us to have an outside director, so we weren't in a particular hurry to appoint one," said Canon public relations officer Jun Misumi.

Benes said companies have also come under pressure to appoint outside directors since Institutional Shareholder Services, a leading proxy adviser firm, began opposing the renewal of chief executives' terms at companies with no independent directors.

Toyota appointed three independent directors last June, its first ever, after critics blamed an insular management style for its slow response to fatal accidents in the United States and recalls of millions of vehicles.

Hitachi Ltd (>> Hitachi, Ltd.), Japan's largest electronics company, reshuffled its board in 2012 to appoint a majority of independent directors for the first time, with three non-Japanese among the newly named outside directors.

Canon also reported quarterly results on Wednesday that fell short of both its own guidance and market expectations, as the boost from a weaker yen, increasing the value of its revenue from abroad, was outweighed by a drop in camera sales.

(Editing by Edmund Klamann and Mark Potter)

By Sophie Knight

Stocks treated in this article : Hitachi, Ltd., CANON INC., Toyota Motor Corp