The present invention provides a microwave treatment apparatus capable of suppressing the occurrence of sparking in a vessel. A microwave treatment apparatus 1 includes: a vessel having a pillar-shaped hollow portion configured to contain a liquid-phase content to be subjected to batch processing using microwaves, and an upper inner face whose height decreases along a direction from a central axis of the hollow portion to the periphery when the vessel is located such that a direction along the central axis is along a vertical direction; a microwave generator that generates microwaves; and a waveguide having a portion protruding from the upper inner face into the hollow portion, and configured to introduce microwaves generated by a microwave generator into the hollow portion.