A microwave treatment apparatus includes a treatment chamber, a microwave supply, and a resonator unit. The treatment chamber is surrounded by a plurality of walls, and accommodates a heating target. The microwave supply supplies a microwave to the treatment chamber. The resonator unit is provided on one wall of the plurality of walls, and the resonator unit has a resonance frequency in a frequency band of the microwave. In this embodiment, the impedance of the surface of the resonator unit can be changed by controlling the frequency of the microwave supplied to the treatment chamber. This makes it possible to control the standing wave distribution within the treatment chamber, that is, the microwave energy distribution within the treatment chamber. As a result, in the cases where a plurality of heating targets need to be heated simultaneously, desired dielectric heating is conducted for each of the heating targets.