Japan has been allowed to enter the Trans Pacific Partnership trade talks by the 11 countries already in negotiations.
Trade Minister Tim Groser announced Japan's entry had been agreed on from Indonesia where TPP talks were held on the sidelines of the APEC trade ministers' meeting.
New Zealand has been cautious about Japan's entry into the talks because of its protectionist policies and high tariffs especially in horticulture and agriculture.
Mr Groser gave New Zealand's final approval after meeting with Japan's Minister of Economic Revitalisation, Akira Amari who had assured him Japan was committed to a comprehensive agreement.
"New Zealand was seeking assurances that Japan is committed to achieveing the ambition that has been set for TPP and could positively contribute to the momentum of the negotiations."