An IC chip for preventing an authentication key from leaking, and an authentication key setting and authentication key verifying method are provided. A part performing connection or disconnection between an external terminal and a smartcard chip may be configured by a separate chip or may be incorporated into the smartcard chip to configure a single chip. When the part is configured by the separate chip, the disconnection between the external terminal and the smart card chip can be performed according to whether an authentication key is verified. When the part is configured by the one chip, the disconnection between the external terminal and the smart card chip can be performed under a control of the smartcard chip according to whether the authentication key is verified.