Japan-based internet users who download copyright infringing files face up to two years in prison or fines of up to two million yen ($25,700; £15,900) after a change to the law.
Such activity has been illegal since 2010, but until now had not invoked the penalties.
It follows a lobbying campaign by country’s music industry.
But critics said that efforts should have remained focused on stopping users making such material available.
Source: BBC News