In 1955, in Hiroshima, the First World Conference against A-and H-Bombs was held, where many Hibakusha reported the actual conditions of atomic suffering before the Japanese and foreign people. The testimonies of all the Hibakusha made a deep impression on the participants and gave them a great shock. After that, Hibakusha began to testify about their experiences all over Japan and sometimes in fereign countiries. As a result of this conference, in 1956, the Japan Confederation of A- & H-Bombs Sufferes Organizations (Hidankyo) was set up. Since then, it has been serving as a national center of Hibakusha movement. In the declaration at the conference of this confederation, they stated that the movement of the people against A-and H-bombs and especially the First World Conference against A-and H-Bombs gave courage to Hibakusha, and that the aim of the confederation is 'to appeal to the world what should be appealed, to demand to the government what should be demanded, to rise up themselves, and to seek the way themselves to relieve one another.' This paper dicusses on the Hibakusha movement of the period between the First World Conference against A-and H-bombs (1955) and the organization of 'Hidankyo' (1956).