There is provided a multi-mode power amplifier operable in a low power mode having a preset power range and in a high power mode having a power range higher than the power range of the low power mode. The multi-mode power amplifier includes: a high power amplifying unit including at least one cascode amplifier to amplify an input signal to a high power level having a preset power range; a low power amplifying unit sharing a common source node of the at least one cascode amplifier to amplify the input signal to a low power level having a power range lower than the high power level; and a coupling unit coupling a transfer path of a signal output from the high power amplifying unit and a transfer path of a signal output from the low power amplifying unit to each other.