A liquid treatment apparatus for treating water to be treated, according to the present disclosure, includes a treatment tank, a dielectric partition wall dividing inside of the treatment tank into a first space in which the water to be treated is injected, and a second space in which an electrolytic solution is filled, a first electrode at least part of which is arranged in the first space of the treatment tank, a second electrode at least part of which is arranged in the second space of the treatment tank, and a power supply that applies a high-frequency AC voltage between the first electrode and the second electrode.