An authentication method characterized by comprising: disclosing, by a tag device (1, 61), a temporary first value indicating identification data attached to an object; referring, by a data reference client (2, 51), to data of the object corresponding to the identification data of the object disclosed by the tag device (1, 61); authenticating, by an authentication server (3, 52), the data reference client (2, 51) and issuing (S302, S305) a temporary second value to the data reference client (2, 51), and reporting the temporary second value to a data server (4, 53); storing, by the data server (4, 53), data of the object corresponding to the identification data and storing the temporary second value reported by the authentication server (3, 52), and authenticating the temporary first value indicating the identification data disclosed by the tag device (1, 61) and the most recent referral of the identification data of the object, generating a new first value according to success of authentication, encrypting the generated new first value with a shared key, and reporting the encrypted new first value to the tag device (1, 61); decrypting, by the tag device (1, 61), the encrypted new first value by using the shared key, storing the decrypted new first value, and disclosing the new first value along with the identification data; storing, by the data reference client (2, 51), the temporary second value and generating a third value by conducting a predetermined calculation with the temporary first value disclosed by the tag device (1, 61) and reporting to the data server the generated third value along with the identification data disclosed by the tag device (1, 61); and conducting authentication, by the data server (4, 53), wherein the data of the object corresponding to the identification data is referred to, by comparing a third value obtained by conducting the predetermined calculation with the first and second temporary values stored in the data server (4, 53) and the third value reported from the data reference client (2, 51). disclosing, by a tag device (1, 61), a temporary first value indicating identification data attached to an object; referring, by a data reference client (2, 51), to data of the object corresponding to the identification data of the object disclosed by the tag device (1, 61); authenticating, by an authentication server (3, 52), the data reference client (2, 51) and issuing (S302, S305) a temporary second value to the data reference client (2, 51), and reporting the temporary second value to a data server (4, 53); storing, by the data server (4, 53), data of the object corresponding to the identification data and storing the temporary second value reported by the authentication server (3, 52), and authenticating the temporary first value indicating the identification data disclosed by the tag device (1, 61) and the most recent referral of the identification data of the object, generating a new first value according to success of authentication, encrypting the generated new first value with a shared key, and reporting the encrypted new first value to the tag device (1, 61); decrypting, by the tag device (1, 61), the encrypted new first value by using the shared key, storing the decrypted new first value, and disclosing the new first value along with the identification data; storing, by the data reference client (2, 51), the temporary second value and generating a third value by conducting a predetermined calculation with the temporary first value disclosed by the tag device (1, 61) and reporting to the data server the generated third value along with the identification data disclosed by the tag device (1, 61); and conducting authentication, by the data server (4, 53), wherein the data of the object corresponding to the identification data is referred to, by comparing a third value obtained by conducting the predetermined calculation with the first and second temporary values stored in the data server (4, 53) and the third value reported from the data reference client (2, 51).