The present invention provides a digital amplitude modulator and polar transmitter using the same. The polar transmitter includes: a polar converter for converting an input signal into an amplitude information signal and a phase information signal, and outputting the converted amplitude and phase information signal; a sigma-delta modulator for receiving a fractional part of the amplitude information signal, and generating a correcting value for an integer part of the amplitude information signal; a phase-modulator for upward-modulating the phase information signal outputted from the polar converter, and outputting carrier waves including the upward-modulated phase information signal; and a digital power amplifier for generating an output signal whose amplitude corresponds to the integer part of the amplitude information signal which is subjected to correction by the correcting value, and outputting combining the output signal with an output value of the phase-modulator to output the combined signal.