A high-frequency heating device of the present invention includes at least one high-frequency power generating part, at least one high-frequency power unit including a quadrature modulation part and a high-frequency power amplification part, a radiation part, a modulation signal generating part, and a control part, and the control part supplies the modulation signal generating part with a plurality of pieces of subcarrier information respectively including pieces of information of offset frequencies and phases, generates an in-phase modulation signal and a quadrature modulation signal, performs quadrature modulation in the quadrature modulation part, and outputs a plurality of subcarrier waves.