The plaintiff, Amelie K, a set decorator, spoke in court after Depardieu, and said the actor had groped her all over her body as he trapped her between his legs and made explicit sexual comments, terrifying her while they were on a film set in 2021.
"He grabbed me and groped me in the front of my body, the back, all around. He trapped me with his legs," she told the court.
"He touched everything, including my breasts," she said.
"I was terrified, he was laughing."
A towering figure of French cinema, Depardieu, 76, has faced a growing number of sexual assault allegations in recent years.
Depardieu's trial is the highest-profile MeToo case in the media industry to come before the courts in France.
He has denied wrongdoing and this is the first case over which he is standing trial.
"Yes, I confirm I grabbed her by the hips to tell her not very nice things but not to grope her," Depardieu said.
Earlier, he had said he had grabbed Amelie K to avoid slipping, as he was tired and upset.
After Amelie K's lawyer said Depardieu had changed his version of events yet again, as he had thus far denied touching her, the actor said: "If you say so."
The actor told the court he was not at ease with how society was evolving.
"I think my time is over," he said.
If found guilty, Depardieu could face a sentence of up to five years in jail and a 75,000-euro ($A129,000) fine.
The second day of the trial was marked by high drama, with Depardieu's lawyer interrupting and screaming at Amelie K's lawyer while Depardieu heatedly denounced the "hysteria" of some women.
Often wandering off topic, Depardieu said he had accused Amelie K of doing her job badly, shocking her, and that any crude comments he made were related to her work.
Amelie K rejected this, saying Depardieu had not criticised her work but had made repeated crude sexual comments and assaulted her.
She said someone - she did not know who - eventually stepped in, freeing her from his grasp and pulling her away.
Prosecutors have given a similar account of what they described as a sexual assault, witnessed by three people.
They said the alleged assaults against Amelie K and another woman - their full identities were not revealed - took place during the 2021 filming of Les Volets Verts (The Green Shutters).
The second woman was groped by Depardieu on set and in the street, prosecutors said.
Depardieu's lawyer Jeremie Assous told reporters on Monday the accusations were false and based on lies.
In court, he accused investigators of bias and wanting to bring Depardieu down.
The accusations against Depardieu and his trial have divided French actors, with some supporting him and expected to speak at the trial, and others backing the plaintiffs.
At the time of the alleged assaults on the set of Les Volets Verts, Depardieu was already under investigation over a rape allegation by actress Charlotte Arnould, who was present in court this week to follow the proceedings.
The Paris prosecutor's office last year said Depardieu should face trial over Arnould's complaint.
Depardieu has denied any wrongdoing.
It is up to an investigative judge to say if there will be a trial over those allegations.
