1. A mobile communication apparatus comprising: a first SIM card, comprising corresponding first identification information, being coupled to the mobile communication apparatus; an anti-theft control circuit comprising: a SIM-card-detection module for detecting whether the first SIM card is replaced by a second SIM card, and generating a corresponding detection result; and an information management module for storing the first identification information corresponding to the first SIM card, a predetermined contact information, and a user personal database; a transmission control circuit for transmitting data and/or signal; and a security module providing a data security class; wherein when the SIM-card-detection module generates the detection result, the transmission control circuit sends out a notice signal according to the predetermined contact information stored in the information management module, and when the security module receives the detection result, a data security procedure in the security module is enabled to protect the data in the user personal database according to the set data security class.