To provide a means for preventing a card from being pulled out, or an unauthorized card from being inserted by a suspicious person, and for preventing electronic equipment from being used illegally while the equipment provided with a card type device insertion slot is put on exhibition.

In a Kensington lock security system, a Kensington lock 7 to be used for the purpose of preventing a theft of an equipment body is coupled with the equipment body and an end of a steel wire 8 fixed to the Kensington lock 7 is coupled with a strong fixed object such as an exhibition table while the electronic equipment is put on exhibition in front of the shop or the like, an outer lid 5 for covering the card insertion slot 2 and an equipment case body are integrally combined with a lock key 7a at the tip of the Kensington lock 7.