The outcome of the trial will be determined by whether the 3 defendants could have predicted a major tsunami such as the one that triggered the nuclear accident at Fukushima Daiichi.
Tokyo Electric Power Company was found to have predicted in 2008 that there was a risk that a tsunami of up to 15.7 meters could hit the plant.
It made the estimate based on an assessment by a Japanese government task force for the promotion of earthquake research.
But the utility failed to take specific measures on the grounds that a tsunami of that scale was unlikely.
In 2012, former TEPCO chairman Tsunehisa Katsumata told the Diet that he did not receive the report of his company's prediction.
The 2 former vice presidents said they were aware of the report, but they maintained that the figure lacked sufficient basis.
The defendants will not be found accountable unless they are found to have neglected their professional duty.
The issue of whether the nuclear accident could have been avoided altogether will also be taken up at the trial.
Both the Diet panel and the government's team of investigators have yet to unveil the contents of the hearings conducted with the 3 officials.