Nuclear ethics is a cross-disciplinary field of academic and policy-relevant study in which the problems associated with nuclear warfare, nuclear deterrence, nuclear arms control, nuclear disarmament, or nuclear energy are examined through one or more ethical or moral theories or frameworks.

Nuclear ethics assumes that the very real possibilities of human extinction, mass human destruction, or mass environmental damage which could result from nuclear warfare are deep ethical or moral problems. Specifically, it assumes that the outcomes of human extinction, mass human destruction, or environmental damage count as moral evils. Another area of inquiry concerns future generations and the burden that nuclear waste and pollution imposes on them. Some scholars have concluded that it is therefore morally wrong to act in ways that produce these outcomes, which means it is morally wrong to engage in nuclear warfare.

Nuclear ethics is interested in examining policies of nuclear deterrence, nuclear arms control and disarmament, and nuclear energy insofar as they are linked to the cause or prevention of nuclear warfare. Ethical justifications of nuclear deterrence, for example, emphasize its role in preventing great power nuclear war since the end of World War II. Indeed, some scholars claim that nuclear deterrence seems to be the morally rational response to a nuclear-armed world. Moral condemnation of nuclear deterrence, in contrast, emphasizes the seemingly inevitable violations of human and democratic rights which arise. In contemporary security studies, the problems of nuclear warfare, deterrence, proliferation, and so forth are often understood strictly in political, strategic, or military terms. In the study of international organizations and law, however, these problems are also understood in legal terms.

Nuclear technology has seen the formation of an anti-nuclear movement since its early development, and grew with the increased impact of it, particularly nuclear weapons testing, caused the deaths of up to 43 thousand people until 2020.

The application of nuclear technology, both as a source of energy and as an instrument of war, has been controversial.

Even before the first nuclear weapons had been developed, scientists involved with the Manhattan Project were divided over the use of the weapon. The role of the two atomic bombings of the country in Japan's surrender and the U.S.'s ethical justification for them has been the subject of scholarly and popular debate for decades. The question of whether nations should have nuclear weapons, or test them, has been continually and nearly universally controversial.

The public became concerned about nuclear weapons testing from about 1954, following extensive nuclear testing in the Pacific Ocean. In 1961, at the height of the Cold War, about 50,000 women brought together by Women Strike for Peace marched in 60 cities in the United States to demonstrate against nuclear weapons. In 1963, many countries ratified the Partial Test Ban Treaty which prohibited atmospheric nuclear testing.

Some local opposition to nuclear power emerged in the early 1960s, and in the late 1960s some members of the scientific community began to express their concerns. In the early 1970s, there were large protests about the proposed nuclear power plant Wyhl, located at the Rhine in south west Germany. The project was cancelled in 1975 and anti-nuclear success at Wyhl inspired opposition to nuclear power in other parts of Europe and North America. Nuclear power became an issue of major public protest in the 1970s.