Abstract: Imaginary defense belongs to grounds for legitimate mistakes in the criminal law theory of continental legal system. The factual mistakes consist of grounds for legitimate mistakes, specific factual mistakes and abstract factual mistakes. In domestic criminal law theory, imaginary defense is classified as behavior nature mistake and included in fact mistakes with object mistake and causality mistake. The problem of classification, however, is not basically solved. From the perspective of its structure and cause, imaginary defense should be classified as object mistake of abstract fact mistake and in such case it is not an intentional crime.