摘要： 一般违法行为之所以虽具有社会危害性却不构成犯罪，在于其不具有刑事违法性，因而犯罪的本质特征不是社会危害性而是刑事违法性，社会危害性、应受刑罚处罚性分别体现刑事违法性的性质与程度。有关但书机能的争论正是有关犯罪本质特征之争的具体体现，但书的实质在于，通过具体判断行为的社会危害性程度来决定是否具有刑事违法性，因而但书规定是入罪限制条件，要求所有入罪行为的社会危害性均不得是“情节显著轻微危害不大”。研究但书机能的目的在于，通过适用但书以区分一般违法行为与刑事违法行为，日本刑法理论中的可罚的违法性理论对此具有参考价值。

关键词: 刑事违法性, 社会危害性, 但书, 可罚的违法性, 犯罪本质

Abstract: The reason why general illegal activities do not constitute a crime which are harmful to the society is that they do not have criminal illegality. As a result, Nature of crime is not social harmfulness but criminal illegality. Social harmfulness and deserving of criminal penalty punishment respectively reflect the nature and the degree of criminal illegality. The arguments about the function of proviso are the concrete reflection of the arguments about the nature of crime. Nature of proviso is to decide whether a behavior is against the Kriminal law by concretely judging its degree of the social harmfulness. Therefore the proviso is the limitation of criminalization, it demands the social harmfulness of all criminal acts shall not be “obviously minor and causing no serious harm”. The purpose of researching the function of proviso is to distinguish criminal offence from general illegal activities by the application of proviso. The theory of punishable illegality in Japanese criminal law theory has some reference value.

Key words: Criminal Illegality, Social harmfulness, Proviso, Punishable illegality, Nature of crime