To improve crime prevention by actuating a relay and an alarm by a specified PIN (personal identification number) code switch with a contact point at the time when a body covering a lock (hole) is removed.

A system to control a relay and an alarm by the PIN code switch with a contact point to detect a back electric route by a front electric route by aligning a three-point type switch arranged as a set of a front and a back in the cross direction is provided. Thereafter, this system is devised to work in the case when a body to cover a lock (hole) is removed by an intruder. Thereafter, the body is made free to use generally by providing a lock part contact point switch free to slide and free to adjust height to judge whether the body is removed or not. Additionally, alarm sound is made to keep sounding once it starts sounding by providing a self holding circuit on the relay. Furthermore, a battery and a PIN code arrangement are covered with a cover so as to prevent the battery from being removed and the code arrangement from being grasped by a back switch. Consequently, it is possible to certainly prevent a fraudulent use of the PIN code number and illegal intrusion.