A plasma processing apparatus includes a processing chamber the inside of which is maintained in a vacuum; a mounting table configured to mount a target substrate and serve as a lower electrode in the processing chamber; a circular ring-shaped member provided at the mounting table so as to surround a peripheral portion of the target substrate; an upper electrode arranged to face the lower electrode thereabove; and a power feed unit for supplying a high frequency power to the mounting table. The apparatus performs a plasma process on the target substrate by plasma generated in the processing chamber. The circular ring-shaped member includes at least one ring-shaped groove configured to adjust an electric field distribution to a desired distribution in a plasma generation space, and the groove is formed in a surface of the circular ring-shaped member and the surface is on an opposite side to the plasma generation space.