Plasma processing apparatus and plasma processing methods capable of maintaining etching characteristics and to prevent degradation of a lower electrode even when the focus ring is severely eroded by the plasma are disclosed. According to an exemplary embodiment, a side-surface protecting ring formed of a ceramic material having an erosion rate by the plasma lower than an erosion rate of the material of the focus ring is provided to cover the side surface of the lower electrode. As a result, it becomes possible to prevent the side surface of the lower electrode from being exposed to the plasma and maintain the etching characteristics even after the focus ring is severely eroded. Further, degradation of the lower electrode is decreased.