Administrative detention is arrest and detention of individuals by the state without trial. A number of jurisdictions claim that it is done for security reasons. Many countries claim to use administrative detention as a means to combat terrorism or rebellion, to control illegal immigration, or to otherwise protect the ruling regime.

In a number of jurisdictions, unlike criminal incarceration (imprisonment) imposed upon conviction following a trial, administrative detention is a forward-looking mechanism. While criminal proceedings have a retrospective focus – they seek to determine whether a defendant committed an offense in the past – the reasoning behind administrative detention often is based upon contentions that the suspect is likely to pose a threat in the future. It is meant to be preventive in nature rather than punitive (see preventive detention). The practice has been criticized by human rights organizations as a breach of civil and political rights.

In other jurisdictions it is retrospective, i.e., it is a form of punishment for a certain category of offenses.