The theory of criminal law has classified criminal omission into omission crime and commission by omission. As for the omission crime, the criminal law not only expressly prescribes the actor/perpetrator, but also defines the criminal omission as a constitutive element. Therefore, the certainly omission crime is completely in accordance with the principle of nulla poena sine lege. However, as it’s known, the recognition of the certainly commission by omission may run against the above principle.