A transmission device includes a pulse modulated signal generator that generates a pulse-modulated signal by changing the width of a pulse or the density of a pulse according to the magnitude of the amplitude component of an input signal while discretely changing the pulse height according to the magnitude of the amplitude, a modulated-signal generator that generates a modulated signal by integrating the pulse-modulated signal and the phase component of the input signal, a power amplifier that includes at least as many amplifiers as the number of the discrete amplitude levels of the modulated signal, changes the number of amplifies that amplify the modulated signal on the basis of the value of the amplitude level of the modulated signal, combines outputs of the amplifiers, and outputs a combined output, and an output filter that eliminates a square-wave component from the output of the power amplifier.