刑法第十六條規定，行為人不得因不知法律而免除刑事責任，除非有正當理由。依照本條的規定，忽視法律不得作為免責的藉口。本文主要討論禁止錯誤的刑法評價問題。禁止錯誤是指，行為人施行違法行為，卻以為並不違法。行為人因此發生了違法性的錯誤，亦即欠缺不法意識。由於刑法的規範幾乎都以禁止的方式表現，所以違法性錯誤也稱為禁止錯誤。禁止錯誤有時不易與事實錯誤區分，本文因此對於兩者先加以分辨。欠缺不法意識的內容究竟何所指，學說各有所見。禁止錯誤的評價，涉及刑法體系的立場。本文因此對於刑法體系也大略做了敘述。本文採取現代刑法體系的罪責理論，認為禁止錯誤不能依過失犯處理，而是成立故意犯罪，僅得依錯誤是否能夠避免，再決定是否減免罪責。學說上有認為，普通刑法上的禁止錯誤可以依照罪責理論處理，但是附屬刑法的禁止錯誤責應當依照過失理論處理。本文則認為，沒有分流處理的必要，應當一律依照罪責理論處理。

The Article 16 of Criminal Code of the Republic of China, ＂Criminal responsibility shall not be excused simply because of ignorance of the law unless there are rightful reasons for being unable to avoid the offense, but the punishment may be reduced according to circumstances.＂, such a description exactly explains the meaning of ignorantia juris non excusat (Latin for ＂ignorance of the law is no excuse.＂) which is a legal principle indicating that anyone cannot escape the liability of violating law just by claiming his unawareness of the contents of law. When a perpetrator claims that he has one or more errors in understanding how the applicable law applied to his behavior that is under analysis by a court, in criminal cases, we call it as ＂mistake of law＂ (Verbotsirrtum). In other words, ＂mistake of law＂ is totally different from ＂mistake of fact.＂ However, in some cases, these two ideas are not easily distinguishable. To clarify the difference between ＂mistake of law＂ and ＂mistake of fact,＂ this study would firstly introduce their essentiality. Secondly, this thesis would make a description of the definite content of ＂illegality cognition.＂ In regards to ＂mistake of law,＂ it means that the perpetrator lacked ＂illegality cognition＂ while he misbehaved. Though ＂illegality cognition＂ has been discussed for ages, the theoretical disputes of ＂illegality cognition＂ still exist. That’s the reason why this study still makes a detailed explanation of ＂illegality cognition＂ to reassure the concept of ＂illegality cognition.＂ Last but not the least, discussing the legal effect in a criminal case which the perpetrator lacks ＂illegality cognition＂ definitely has something to do with the opinions of ＂the guilt theory＂ and ＂the intention theory.＂ As a supporter of ＂the guilt theory,＂ the author of this study indicates that only the ＂inevitable mistake of law＂ could cause the law effect of negating the perpetrator’s guilt. Otherwise, the perpetrator still commits the crime and this perpetrator, without a doubt, would be penalized by criminal norms.