To provide a lock (cylinder) and a key which allows the owner of the key to easily obtain information on repair of the lock via a portable telephone and to quickly take necessary measures, such as making contact with a repair man, for instance, even if he has lost the key or the lock or suffers from an abnormality of the lock so that a door of an entrance does not open, resulting in impossibility of entering a house at midnight, and to provide a lock information providing system.

According to the lock information providing system, a portable web site URL for providing information concerning the lock, including an advertisement of repair of the lock and the lock per se, and information, etc., concerning an agent dealing with the lock and a lock repairing shop, is indicated at least on one of the lock (cylinder) and the key. Further, the system is comprised of a telephone center or an automatic receiving device dealing with provision of the information concerning the lock, including the advertisement of the repair of the lock and the lock per se, and the information, etc., concerning the agent dealing with the lock and the lock repairing shop, and a telephone number of the telephone center or the automatic receiving device is indicated at least on one of the lock (cylinder) or the key.