Personal legal interest shall not be principally punished when victim consents to infringement upon his own legal interest. The consent that has been made by either violence and threat or deception and misunderstanding may have problem of legal effect because it has not been made based on truly free will of legal interest entity. The paper has discussed legal effect of the consent made by misunderstanding. Theories are divided into three: theory of serious misunderstanding(theory of subjective real intention), theory of misunderstanding of the motives and theory of legal interest related misunderstanding, depending upon situation that an misunderstanding has been made. The consent based on misunderstanding of ‘legal interest itself’ of legal interest entity shall be null and void, and the consent made by misunderstanding of ‘incidental circumstances such as motives and purposes’ shall be effective according to theory of legal interest related misunderstanding that is thought to be the most appropriate. However, theory of legal interest related misunderstanding may be difficult to consistently explain specific case such as ‘misunderstanding of emergent situation’. Some of scholars admit of an exception that theory of legal interest related misunderstanding cannot solve all of the cases: However, different theory construction of each case that can maintain theoretical structure of theory of legal interest related misunderstanding is thought to be desirable. So called ‘the case of killing of wild beasts’ has shown that objective value of wild beasts can be lowered under emergent situation to decrease needs of legal interest protection. Therefore, a breeder who has consented killing of wild beasts by deceptive behavior may have misunderstanding of legal interest relations to nullify consent. So called ‘the case of corneal transplant’, however, does not deteriorate legal interest values even at existence of emergent situation to let legal interest entity have freedom of disposal of legal interest so that it may be different from the case of killing of wild beasts. The resolution may have many opinions: But the opinion nullifying consent that an error of ‘general value system’ is regarded to be that of legal interest relations is thought to be the most appropriate considering maintenance of theory of legal interest related misunderstanding.