A mobile terminal and method of controlling a driving voltage of a power amplifier therein are provided. The present invention includes a power amplifier module having a plurality of operative modes, the power amplifier module configured to amplify a power strength of an RF signal, a modem configured to deliver the RF signal to the power amplifier module, and to control the operative modes of the power amplifier module, a power detecting unit configured to output a reference voltage by detecting the power strength of the RF signal outputted from the power amplifier module, and a DC/DC converter configured to supply a driving voltage to the power amplifier module by adjusting a detected power value according to a gain corresponding to each of the operative modes of the power amplifier module.