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) after a change to the law, BBC News reported.
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 U.S.
Japan's action is part of a wider international crackdown on online piracy.
Over recent months the U.S. has taken the digital locker service Megaupload offline; Ukraine has shut down the BitTorrent site Demonoid; the UK has jailed the owner of the Surfthechannel video link provider; and several countries have restricted access to The Pirate Bay torrent service – the founder of which was recently deported from Cambodia to Sweden to face tax charges.
France also recently fined one of its citizens for the first time under its "three strikes" rule which allows it to impose a fine if a suspected pirate ignores three warnings about their activity.
However, attempts to introduce new laws have run into problems elsewhere.
The U.S. put off votes on Sopa (Stop Online Piracy Act) and Pipa (Protect IP Act) in January after Wikipedia and thousands of other sites staged blackouts in protest.
The European Parliament also voted to reject Acta (Anti-Counterfeiting Trade Agreement) in July after opposition across the continent.
