A high-frequency power supply includes a shaft bonded to one surface of a plate serving as a gas distributor plate. The plate includes a radio-frequency electrode buried therein. The shaft has a through-hole through which a gas flows. The plate and the shaft are made of a ceramic material. The shaft has a double-tube structure including the inner tube and the outer tube . The interior space of the inner tube forms the through-hole. The plate is hermetically solid-state bonded to the inner tube and the outer tube. The shaft is bonded to the center of the plate.