The microwave heating apparatus of the present invention enables microwaves to be propagated onto an object to be heated through a waveguide such that the microwaves propagate to a microwave space reduced by a wavelength controller which is arranged, as a solid-state object, to occupy a predetermined space in the waveguide. Thus, the microwave heating apparatus of the present invention heats the object to be heated which has been placed in the reduced space. The microwave heating apparatus of the present invention utilizes the effects of lengthening the wavelength of the microwaves propagating to the reduced space so as to be longer than the wavelength before entering the reduced space by a predetermined multiple depending on a near-cutoff condition.