The move came after a one-season suspension of its hunting in the ocean as the United Nations' top legal body judged last year that Japan's whaling there was a fig leaf for a commercial hunt.
Japan's fisheries agency has since told the International Whaling Commission that it would resume whaling in the Antarctic Ocean by cutting annual minke whale catches by two-thirds to 333 this season.
Japan's agency decided on Friday however to go ahead with the plan, claiming that it was scientifically adequate and no change was needed, Kyodo News said.
The Yomiuri Shimbun and other media said Japanese whalers were expected to depart for the ocean possibly by the end of December.
There was no immediate comment from the agency.
Despite international disapproval, Japan has hunted whales in the Southern Ocean under an exemption in the global whaling moratorium that allows for lethal research.
However, the highest court of the United Nations, the International Court of Justice, ruled in March 2014 that the annual Southern Ocean expedition was a commercial hunt masquerading as science to skirt the international moratorium.
Respecting the judgement, Japan sent whaling ships to the ocean last season but they returned with no catch.
It accuses opponents of being emotional about whales and disregarding what it says is evidence to support its position.
