The present invention provides a mobile phone for authenticating Subscriber Identification Module (SIM) card and a SIM card authentication method adapted for the mobile phone. Once a SIM card is inserted into the mobile phone, the mobile phone acquires a phone number associated with the inserted SIM card and identifies whether the acquired phone number has been stored in the non-erasable programmable memory of the mobile phone. If yes, the user is legal and can use the mobile phone, if no, then the user is illegal and cannot use the mobile phone. Therefore, the mobile phone protects and hides stored information from the user.