To what extent can legal exercise of state power ever be justified? There are so many answers to this question including anarchism, liberalism, communitarianism, totalitarianism etc. Among them, paternalism, strictly speaking, legal paternalism is one of the most reasonable and plausible solutions. It justifies legal exercise of state power to protect a person from self-regarding harm against one`s will. Paternalism can be defined broadly as `a interference with another for his own good`. It can be classified such pairs of concepts as hard/soft paternalism, physical/moral paternalism, strong/weak paternalism, positive/negative paternalism, passive/active paternalism etc. Legal moralists argue against paternalism, while liberals who abhor moral legalism also criticise it. According to harm principle based on classical liberalism, liberty-limiting interference can be justified to protect a person from not self-regarding harm, but other-regarding harm. But, legal moralism justifies liberty-limiting interference in order to protect a common morality itself as well as a person from harms. In a sense, paternalism contradicts harm principle on the one hand, legal moralism on the other hand. It paradoxically means that paternalism can be compatible with harm principle as well as legal moralism. Can paternalism really coexist with harm principle or legal moralism? A conceptual-analytic study on paternalism is necessary to answer to the question.