This study is to scrutinize the social structure which surrounds Vittoria, the female protagonist in The White Devil, and the process through which she is defined as a victim. The White Devil deals with the struggle of a woman who refuses to be unjustly defined as a "whore" or "devil" by the patriarchal society. Vittoria tries to keep her selfhood by revealing the fact that her social identity as a whore is not based on any truth but socially has been "constructed" by patriarchal authorities. Dramatic methods, such as the trial scene or arguments, clearly show us the way patriarchal authorities fortify the oppression of women by "constructing" female sexuality as socially destructive. On the other hand, because Vittoria defends herself with the same rhetorical strategy as her accusers, which hides truth under the cover of authorities, we cannot simply evaluate her as an admirable heroine who overcomes the oppression of a patriarchal society. Nonetheless, Vittoria's effort to keep her selfhood, or in other words, her powerful self-assertion, is a subversive energy which can pose a fundamental question about the basic structure of patriarchal society, revealing the hidden mechanism with which patriarchal authorities dominate womankind