This is a case study of the legislation of anti-nuclear policy in order to outline the merits and demerits of it offset each other. First, the paper describes the evolutions of New Zealand's initiatives towards the establishment of international legal-framework for the nuclear-free world. The history shows that New Zealand's anti-nuclear policy has started from the real fear for the nuclear weapons testing in the South Pacific, and converged to the ideal policy which was reflected its national identity. Second, the paper surveys the process of legislation, which originated from the policy of New Zealand Labour Party in 1984 and concluded at the New Zealand Nuclear Free Zones, Disarmament, and Arms Control Act 1987. Over-viewing it, the climax at the international stage, which is called 'the ANZUS Crisis' between New Zealand and the U.S., is boldly examined. Third, the various arguments over the New Zealand Nuclear Free Zones, Disarmament, and Arms Control Act 1987 are critically introduced. In conclusion, the implication for Japan is pursued. The lessons through the New Zealand's case are underlined.