Provided is a lower power and high efficiency millimeter-wave modulation apparatus capable of modulating digital data into transmitting signals in a millimeter frequency band, the millimeter-wave modulation apparatus including; a modulation part, which carries out a modulation of a constant envelope attribute, and to which a first local oscillation signal is fixed according to a rate of input data; a phase shifter adopted to shift a phase of an output of the modulation part; a power amplifier adopted to amplify an output of the phase shifter; and an antenna connected to an output of the power amplifier.