A high-frequency heating device (100, 200, 300, 400) for heating an object to be heated housed in a heating chamber comprising: at least one high-frequency power generating part being configured to generate a high-frequency power of a set frequency; at least one high-frequency power unit (130, 330) including a quadrature modulation part (131, 231a, 231b, 431a, 431b) being configured to modulate a high-frequency power generated by the high-frequency power generating part with an input modulation signal, and a high-frequency power amplification part (132, 232a, 232b, 432a, 432b) being configured to amplify a high-frequency power modulated by the quadrature modulation part (131, 231a, 231b, 431a, 431b) to an amplitude of power suitable for heating; at least one radiation part being configured to radiate a high-frequency power output from the high-frequency power unit (130, 330) to the object to be heated; a modulation signal generating part being configured to generate a modulation signal supplied to the quadrature modulation part (131, 231a, 231b, 431a, 431b) based on input information of pluralities of frequencies and phases; and a control part (110, 210, 310, 410) being configured to set a reference frequency of a high-frequency power radiated from the radiation part in the high-frequency power generating part, the control part outputting information of individual frequencies and phases of a plurality of high-frequency powers radiated from the radiation part to the modulation signal generating part, the control part (110, 210, 310, 410) being configured to supply the modulation signal generating part with a plurality of pieces of subcarrier information respectively including pieces of information of offset frequencies and phases relative to the reference frequency for a plurality of high-frequency powers radiated from the radiation part at the same time, the modulation signal generating part being configured to generate an in-phase modulation signal and a quadrature modulation signal based on the plurality of pieces of subcarrier information supplied from the control part (110, 210, 310, 410), the modulation signal generating part outputting the in-phase modulation signal and the quadrature modulation signal to the quadrature modulation part (131, 231a, 231b, 431a, 431b), the quadrature modulation part (131, 231a, 231b, 431a, 431b) being configured to perform quadrature modulation of a high-frequency power input from the high-frequency power generating part with the in-phase modulation signal and the quadrature modulation signal input from the modulation signal generating part, the quadrature modulation part (131, 231a, 231b, 431a, 431b) being further configured to output a plurality of subcarrier waves of the offset frequencies and the phases relative to the reference frequency. at least one high-frequency power generating part being configured to generate a high-frequency power of a set frequency; at least one high-frequency power unit (130, 330) including a quadrature modulation part (131, 231a, 231b, 431a, 431b) being configured to modulate a high-frequency power generated by the high-frequency power generating part with an input modulation signal, and a high-frequency power amplification part (132, 232a, 232b, 432a, 432b) being configured to amplify a high-frequency power modulated by the quadrature modulation part (131, 231a, 231b, 431a, 431b) to an amplitude of power suitable for heating; at least one radiation part being configured to radiate a high-frequency power output from the high-frequency power unit (130, 330) to the object to be heated; a modulation signal generating part being configured to generate a modulation signal supplied to the quadrature modulation part (131, 231a, 231b, 431a, 431b) based on input information of pluralities of frequencies and phases; and a control part (110, 210, 310, 410) being configured to set a reference frequency of a high-frequency power radiated from the radiation part in the high-frequency power generating part, the control part outputting information of individual frequencies and phases of a plurality of high-frequency powers radiated from the radiation part to the modulation signal generating part, the control part (110, 210, 310, 410) being configured to supply the modulation signal generating part with a plurality of pieces of subcarrier information respectively including pieces of information of offset frequencies and phases relative to the reference frequency for a plurality of high-frequency powers radiated from the radiation part at the same time, the modulation signal generating part being configured to generate an in-phase modulation signal and a quadrature modulation signal based on the plurality of pieces of subcarrier information supplied from the control part (110, 210, 310, 410), the modulation signal generating part outputting the in-phase modulation signal and the quadrature modulation signal to the quadrature modulation part (131, 231a, 231b, 431a, 431b), the quadrature modulation part (131, 231a, 231b, 431a, 431b) being configured to perform quadrature modulation of a high-frequency power input from the high-frequency power generating part with the in-phase modulation signal and the quadrature modulation signal input from the modulation signal generating part, the quadrature modulation part (131, 231a, 231b, 431a, 431b) being further configured to output a plurality of subcarrier waves of the offset frequencies and the phases relative to the reference frequency.