An apparatus and method for controlling a Multi-Function Device (MFD) of a mobile terminal has a filter circuit converted according to operation modes of the MFD and the apparatus includes a differential amplifier for amplifying an audio signal, an audio filter comprising first and second audio filters connected to the differential amplifier, for varying frequency of the audio signal according to a control signal of the operation modes of the mobile terminal and a switching unit for switching the audio signal with one of the plurality of filters according to the control signal of operation modes. Also, there is an advantage that the apparatus in accordance with the present invention can prevent erroneous performance of the MFD and achieve efficient performance by generating an audio signal classifying frequency characteristic and amplifying gain of the audio filter according to the modes of vibration output, melody output and speech output.