Japanese camera and medical equipment maker Olympus and three of its former executives have pleaded guilty over charges related to a $1.7 billion accounting cover-up.
The case represents one of Japan's biggest corporate scandals.
It was exposed last October by chief executive Michael Woodford, who was sacked by the Olympus board after querying dubious deals later found to have been used to conceal the losses.
"The full responsibility lies with me and I feel deeply sorry for causing trouble to our business partners, shareholders and the wider public," ex-chairman Tsuyoshi Kikukawa told the Tokyo district court.
"I take full responsibility for what happened," he added.
Prosecutors charged Kikukawa, former executive vice-president Hisashi Mori and former auditor Hideo Yamada with inflating the company's net worth in financial statements for five fiscal years to March 2011.
The three former executives had been identified by an investigative panel, commissioned by Olympus, as the main suspects in the fraud seeking to cover up losses on risky investments made in the late-1980s.
The former executives could face up to 10 years in jail and fines of up to 10 million yen (€100,000). The company could be fined more than 100 million yen, according to the Japanese media.
Olympus has already admitted it used improper accounting to conceal massive investment losses under a scheme that began in the 1990s.
In December, it filed five years' worth of corrected financial statements plus overdue first-half results, revealing a $1.1 billion dent in its balance sheet.
