Falsification and repudiation of personal information ransmitted/received for circulation cannot be prevented when there is no trusted third party. A personal information managing device issues a personal information registration certificate corresponding 1:1 to personal information and sends the certificate to a service providing device through a user terminal. When personal information is transmitted/received, the user terminal and the service providing device check the relationship between the certificate and the personal information, thus the user terminal and the personal information receiving device can confirm whether or not the personal information has been falsified. When the personal information is transmitted/received, the personal information is always encrypted. After the encrypted personal information is transmitted/received, the decryption key is transmitted/received. By using the transmission/reception of the decryption key between the personal information managing device and the service providing device as a personal information reception confirmation message, repudiation of personal information transmission/reception can be prevented.