To provide a crime prevention device for preventing theft damage from occurring due to door closing forgetting, 'being opened' of the door with an illegal method and key duplication with an illegal method by solving the problem on 'opening' and 'closing' operations of the door of a case or the like and also monitoring the door.

In door locking and releasing operations, not a key but a crime prevention system releasing mechanism 1a (card device 1b) installed in the case or the like is used to release a locked door with the operation of a controller 2a and to return the door to a locked state with the operation of a state monitoring mechanism 3. In a monitoring device in which a sensor of the state monitoring mechanism 3 senses abnormality and basically performs warning with warning sound (light), each mechanism of a crime prevention mechanism is mounted on the case or the like to be used as a crime prevention device.