To attain crime prevention while keeping the function or character of communication network system by periodically checking the identity of user by reading an iris pattern through a reader and inputting a password from a password input device.

In the case of first use, data compressed by a data compressor 5 are stored in a data storage device 6 while using a reader 1 for iris pattern or the like, connecting means 2 for inputting personal data from the reader 1, password input device 3, connecting means 4 for inputting password data and data compressor 5. In the case of following use, the personal data compressed by the data compressor 5 are compared with the personal data stored in the data storage device 6 by a data comparator 7. When these data are equal, corresponding to the data from the password data input device 3, a permit signal is outputted to a data generator 8 and a generated identification signal and personal data are outputted through a connecting means 9 to the outside.