A plasma processing apparatus includes a high frequency antenna having first and second antenna elements. One end of the first antenna element is grounded and the other end thereof is connected to a high frequency power supply. One end of the second antenna element is an open end and the other end thereof is connected to either one of the one end and the other end of the first antenna element, a line length of the second antenna element having a value obtained by multiplying ((λ/4)+nλ/2) by a fractional shortening (λ is a wavelength of high frequency in vacuum and n is a natural number). A circuit viewed from the high frequency power supply toward the high frequency antenna is configured to generate, when a frequency of a high frequency power is changed, two resonant frequencies by an adjustment of the impedance adjustment unit.