The decision, which will be officially announced as early as next week, comes after decades of confrontation between pro- and anti-whaling members of the IWC.
"We're going to continue to press the worldwide community to bring an end to the unjustified persecution of whales for commercial profit wherever it occurs", she said.
The IWC adopted the moratorium in 1982 to preserve whales and Japan suspended commercial whaling in 1988.
For many years Japan has hunted whales for what it calls "scientific research" and to sell the meat, a programme widely criticised by conservationists.
Japan annually consumes about 5,000 tons of whale meat from the research hunts, mainly by the older generation who feel nostalgic about the meat.
If withdrawing, Japan has to notify IWC by January 1, according to Kyodo News.
"The International Whaling Commission is the body that is recognised under international law as being responsible for the conservation and management of whales", she said.
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To leave the IWC in 2019, Japan needs to notify the commission by Jan 1.
According to Kyodo, Tokyo is now planning, next year, from the Commission to withdraw the commercial hunting of marine mammals.
Conservation campaigners welcomed the possible end to whaling in the Southern Ocean but warned that by withdrawing from the IWC, Japan risked becoming a "pirate whaling nation".
Its rationale could be also questioned as it is a member of the U.N. Convention on the Law of the Sea that calls for the use and conservation of marine resources via global organizations.
The following is a chronology of events related to Japan's whaling.
Except for Japan, Norway and Iceland catch whales - both Nations fish in the North Atlantic and do not see the IWC rules-bound.
Japan has previously threatened to quit the IWC, arguing that the moratorium was supposed to be a temporary measure and accusing the IWC of abandoning its original goal - managing the sustainable use of global whale stocks.
Slooten described the IWC, in its current form, as a "halfway house" that manages whaling and whale conservation, but is dominated by a "very narrow-minded approach to how to interact with whales". Japan would mainly hunt in its own waters.