Magistrates have criticised the bill, fearing it will be hard to define what exactly constitutes such mental abuse and say it will be very difficult to prove in court.
The law was proposed by members of parliament from both the ruling majority and the left-wing opposition and won the backing of the centre-right government.
"We have introduced an important measure here, which recognises psychological violence, because it isn't just blows (that hurt) but also words," Nadine Morano, the minister for family affairs, told the lower house of parliament yesterday.
Anyone found guilty of breaking the new law faces up to three years in jail and a €75,000 fine.
The bill defines mental violence as "repeated acts which could be constituted by words or other machinations, to degrade one's quality of life and cause a change to one's mental or physical state".
Ms Morano said witnesses could be called on to testify in such cases, and doctors' certificates detailing their patients' descent into nervous depression could also be used as evidence.
"The judge could (also) take into consideration letters, SMSs or repetitive messages, because one knows that psychological violence is made up of insults," she added.
The law can be used to protect both women and men who might suffer from such abuse, however parliamentarians have acknowledged that women are the main victims of domestic violence.