The present invention is to provide a system for enabling a user to know whereabouts of his or her missing mobile phone, which comprises a mobile phone and a remote controller. The mobile phone comprises a control module including a wireless transceiver unit for receiving a wireless search signal transmitted from the remote controller and adapted to convert the received wireless search signal into an instruction for controlling an output unit of the mobile phone consisting of a light emitting unit, a drive unit, an audio unit, and/or a display unit to generate corresponding light, vibration, sound, and/or display characters for alerting the user. The remote controller comprises a button which, when pressed by the user, causes the remote controller to generate the wireless search signal and transmit the same to the mobile phone for executing the corresponding instruction.