A high-frequency treatment apparatus includes a treatment high-frequency wave output unit configured to output a treatment high-frequency wave to be applied to a treatment target living tissue, a detection unit for detecting an impedance of the treatment target living tissue, and a control unit configured to control the treatment high-frequency wave output unit on the basis of the result of the detection in the detection unit, the control unit configured to set a treatment frequency of the treatment high-frequency wave to a first treatment frequency in order to treat the living tissue primarily by Joule heat when the impedance of the treatment target living tissue is lower than a threshold value and to set the treatment frequency to a second treatment frequency higher than the first treatment frequency in order to treat the living tissue primarily by high-frequency dielectric heating when the impedance of the treatment target living tissue is higher than the threshold value.
