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.
In Japan illegal uploads of copyright infringing music and videos carry a maximum 10 year prison sentence and a 10 million yen fine.
Sales figures suggest the country is the world's second-largest music market after the US.
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