A data storing system is provided, wherein the data storing system includes: a user apparatus; an issuing apparatus which issues a registration certificate; a data providing apparatus; an issuer registration apparatus; and a data registration apparatus; wherein the user apparatus includes: a part which generates registration information on a key including a user public key, sends the registration information to the issuing apparatus with user information; and a part which verifies a registration certificate, received from the issuing apparatus, which is signature information of the issuer for the registration information and the user information, stores the registration certificate to a storage device when the registration certificate is verified; wherein the issuing apparatus includes a part which generates the registration certificate and sends the registration certificate to the user apparatus.