A transmission device includes an RQAM modulating unit that has an S/P that divides a transmitting signal indicating information to be transmitted into a first signal and a second signal, a mapping unit that maps the first signal into a first in-phase component and a second in-phase component and the second signal into a first orthogonal component and a second orthogonal component by a predetermined mapping system, a P/S that generates a first modulated signal including the first in-phase component and the first orthogonal component and a second modulated signal including the second in-phase component and the second orthogonal component, an IFFT that transmits the first modulated signal and the second modulated signal, a DAC, an LPF, a Mixer, a BPF, and a LOCAL OSCILLATOR.