刑法（英语：criminal law）是规定什幺是犯罪及对犯罪行为处以何种刑罚（即相对应法律效果）的法律。

在各类部门法当中，刑法的历史可以说是最为悠久。近代大陆法系的刑法遵循罪刑法定原则。刑法的渊源主要为刑法典，单行刑法，附属刑法。国际条约并不能直接成为国内法院定罪量刑的依据，各国必须将其签署加入的国际条约中的犯罪行为规定到本国刑法当中，才能对国际罪行进行管辖。

Criminal law or penal law is the body of law that relates to crime. It regulates social conduct and proscribes whatever is threatening, harmful, or otherwise endangering to the property, health, safety, and moral welfare of people. It includes the punishment of people who violate these laws. Criminal law varies according to jurisdiction, and differs from civil law, where emphasis is more on dispute resolution and victim compensation than on punishment.