Japan’s political decision-making process is determined by the characteristics of Japanese parliament and cabinet system，as well as the decision-making mechanism within prime minister’s office under the Abe administration. The new security related legislation is constraint by the political factions within LDP and the Komeito Party. The Abe administration works in suppressing the opposition with LDP and contains the influence of the Komeito Party in order to promote the legislation. However，the Komeito Party，based on the interest of its political backing group，has made a great amount of revision of the new security bills proposed by the government and LDP，reserving the partial restriction of the 9th article of pacifist constitution on Japanese overseas military action. from the perspective of the new security legislation，the characteristics of decision-making mechanism within the prime minister’s office set up by Prime Minister Abe，as well as its direct impact on the decision-making process within LDP，can be seen and understood.