A microwave treatment apparatus (20A; 20B; 20C) comprising: a treatment chamber surrounded by a plurality of walls and configured to accommodate one heating target or a plurality of heating targets (8, 9); a microwave supply configured to supply a microwave to the treatment chamber; and a resonator unit provided on one wall of the plurality of walls and having a resonance frequency in the frequency band of the microwave, wherein the resonator unit includes one or more patch resonators each comprising a dielectric and a conductor, the patch resonators having a characteristic such that the phase difference between the microwave incident on the conductor and the microwave reflected on the conductor is dependent on the frequency of the microwave incident on the conductor, the phase difference being the reflection phase of the resonator unit; wherein the microwave supply includes: a microwave generator configured to generate the microwave; and a controller configured to control the microwave generator to adjust the oscillation frequency of the microwave, wherein by controlling the oscillation frequency of the microwave, the reflection phase of the resonator unit is changed so that the standing wave distribution within treatment chamber can be controlled; and wherein the controller is configured to cause the microwave generator to change the oscillation frequency, based on input information, to be a frequency for more intensively heating at least one of the plurality of heating targets (8, 9), a frequency for uniformly heating the plurality of heating targets (8, 9), or a frequency for heating a central portion of the one heating target more strongly or more weakly than a peripheral portion of the one heating target. a treatment chamber surrounded by a plurality of walls and configured to accommodate one heating target or a plurality of heating targets (8, 9); a microwave supply configured to supply a microwave to the treatment chamber; and a resonator unit provided on one wall of the plurality of walls and having a resonance frequency in the frequency band of the microwave, wherein the resonator unit includes one or more patch resonators each comprising a dielectric and a conductor, the patch resonators having a characteristic such that the phase difference between the microwave incident on the conductor and the microwave reflected on the conductor is dependent on the frequency of the microwave incident on the conductor, the phase difference being the reflection phase of the resonator unit; wherein the microwave supply includes: a microwave generator configured to generate the microwave; and a controller configured to control the microwave generator to adjust the oscillation frequency of the microwave, wherein by controlling the oscillation frequency of the microwave, the reflection phase of the resonator unit is changed so that the standing wave distribution within treatment chamber can be controlled; and wherein the controller is configured to cause the microwave generator to change the oscillation frequency, based on input information, to be a frequency for more intensively heating at least one of the plurality of heating targets (8, 9), a frequency for uniformly heating the plurality of heating targets (8, 9), or a frequency for heating a central portion of the one heating target more strongly or more weakly than a peripheral portion of the one heating target. a microwave generator configured to generate the microwave; and a controller configured to control the microwave generator to adjust the oscillation frequency of the microwave, wherein by controlling the oscillation frequency of the microwave, the reflection phase of the resonator unit is changed so that the standing wave distribution within treatment chamber can be controlled; and wherein the controller is configured to cause the microwave generator to change the oscillation frequency, based on input information, to be a frequency for more intensively heating at least one of the plurality of heating targets (8, 9), a frequency for uniformly heating the plurality of heating targets (8, 9), or a frequency for heating a central portion of the one heating target more strongly or more weakly than a peripheral portion of the one heating target.