For major Japanese thinkers from the Meiji period to the postwar period, peace was an ideal value that had been represented by the ideas of “no- war”(非戰), “anti-militarism(反軍國主義),” and “non-nuclear(非核)”. The voices to eliminate, or reduce, the possibility of physical violence were a key to the Japanese peace discourse, while opposing the expansion of militarism through war and its violent killing. The concept of peace of Japan in the second half of the 20th century can be summarized not only as a process of anti-nuclear movement but also as a campaign to defend Article 9 of the Constitution which renunciation of war was expressed while reflective awareness of Japan’s responsibility for the war arose and the renunciation of weapons, such as nuclear, was proclaimed. Understanding peace as no-war, anti-militarism, and denuclearization means that, in reality (of the 20th century of Japan), the opposite trends, such as war, militarism, and nuclear power, were superior. Practically, Japan continued to wage wars for 78 years from the Meiji period to the defeat in the Pacific War. The war was justified and even, regarded as just. In reality, ‘peace by power always prevailed. Although the negative prefixes such as ‘no-’, ‘non-’, and ‘anti-’ as in no-war, non-nuclear, and anti-militarism have never been mainstream; nevertheless, peace-related voices in Japan has been continuing to have a say in warning and criticizing the expansion of physical - and in particular, military - power. With these circumstances in mind, this paper would like to summarize the history of the concept of peace in Japan. This paper will examine historical streams to see who raised and inherited the peace or its values, how Japanese have imagined the meaning of peace over the past centuries, and what the concepts that correspond to the origin of Japanese peace were. Especially, this paper will look at how Japanese thinkers(Yoshino Sakuzo, Yanaihara Tadao, Kagawa Toyohiko, Article 9 of the Japanese Constitution(日本国憲法第9条), Maruyama Masao as well as Ando Shoeki, Yokoi Shonan, Nakae Chomin, Ueki Emori, Kotoku Shusui, Uchimura Kanzo and so on) in『A Compendium of Japan Peace Theory』(日本平和論大系), a monument to Japan s pacifism, imagined peace. This shows that Japanese pacifists have generally criticized imperialism, militarism, capitalism, and dictatorship, and raised voices toward no/anti-war and rejection of conscription based on freedom, civil rights, socialism, and Christianity. This paper will also look into the present state of Japanese pacifism, which has been subdivided into the movement for the defense of Article 9 of the Constitution, denuclearization, and/or anti-nuclear movements.