A Tokyo court has ruled that Nissan's former chairman, Carlos Ghosn, and another executive will remain in custody until December 20, more than a month after their arrest.
Their detention could continue for months more under the Japanese legal system.
Tokyo District Court said it had rejected a protest filed by Ghosn's lawyer against the prolonged detention.
The court decision came a day after Ghosn, fellow Nissan executive Greg Kelly and Nissan Motor were charged with violating financial laws by underreporting Ghosn's pay by about 5 billion yen (€38.9m) in 2011/15.
They were arrested on November 19 and are being held at a Tokyo detention centre.
The extension of their detention is to allow time for investigations into additional allegations prosecutors issued on Monday, against Ghosn and Kelly, of underreporting another 4 billion yen (€31m) in 2016/18.
The arrest of the man credited with saving Nissan when it was on the verge of bankruptcy two decades ago has stunned many and has raised concerns over the Japanese car maker and the future of its alliance with Renault of France.
No trial date has been set as is routine in Japan.
Prosecutors can add more allegations to extend detention, and it remains unclear when Ghosn and Kelly might be released.
The prosecutors say they consider the two men flight risks.
Ghosn's legal team has not issued an official statement, but those close to him have said he is asserting his innocence.
The US lawyer for Kelly, Aubrey Harwell, has said his client insists he is innocent and that Nissan insiders and outside experts had advised him that their financial reporting was proper.
The maximum penalty for violating Japan's financial laws is 10 years in prison, a 10 million yen (€77,000) fine, or both.
The conviction rate in Japan is over 99%.
Nissan has said an internal investigation found three types of misconduct: underreporting income to financial authorities, using investment funds for personal gain, and illicit use of company expenses.
Nissan, as a legal entity, was also charged.
The firm is not under supervision or being monitored, although it is co-operating with the prosecutors' investigations, according to company spokesman Nicholas Maxfield.
Nissan said in a statement that it takes the indictment "extremely seriously", and promised to strengthen its governance.