To provide a biometric key which can improve the problems in prior art that it is not any multi-purpose key in the sense that its application is limited to specific applications, that the use of an additional structure is required for some special application, etc.

A biometric key has a key body with a built-in biometric sensor. A receiving body engaging with this biometric key is also offered. A reader has slots for maintaining this key. When this key engages with the receiving body, the signal representing the biocode of the data generated by this biometric key is transmitted to a processing means to allow access to the user.