犯罪意识（拉丁文：Mens rea；英文意为guilty mind），简称犯意，又称犯罪意图、不法意图、不法意识，是行为人对其行为本身或行为结果所具有的故意、鲁莽、或明知的内心状态，是刑法上犯罪构成要件之一，属于特殊主观构成要件要素。

某些犯罪，必须具备不法意图，始能成立。例如《中华民国刑法》第320条前段规定，「意图为自己或第三人不法之所有，而窃取他人动产者，为窃盗罪」；若行为人窃取他人动产之目的不在「所有」（管领、支配、处分）、而在于「暂时使用」，此称为「使用窃盗」，因欠缺法定意图，故「构成要件不该当」（不合乎构成要件），无法成立犯罪。

Mens rea (/ˈmɛnz ˈriːə/; Latin for "guilty mind") in criminal law, is viewed as one of the necessary elements of some crimes. The standard common law test of criminal liability is usually expressed in the Latin phrase, actus reus non facit reum nisi mens sit rea, which means "the act is not culpable unless the mind is guilty". Thus, in jurisdictions with due process, there must be an actus reus, or "guilty act", accompanied by some level of mens rea to constitute the crime with which the defendant is charged (see the technical requirement of concurrence). As a general rule, criminal liability does not attach to a person who merely acted with the absence of mental fault. The exception is strict liability crimes.