Provided are a mobile communication terminal having a tag read function and a method of providing genuine product authentication service. The mobile communication terminal having the tag read function specifies an encryption key corresponding to an encryption key stored in the tag from its own plurality of encryption keys based on a signal received from the tag. The mobile communication terminal receives an encrypted product code or product information from the tag and decrypts the received product code or product code using an encryption key. Also, the mobile communication terminal outputs a result of decryption on a liquid crystal display (LCD) window or as beep sounds or voices.