A plasma processing apparatus configured to perform plasma processing on a conductive workpiece having a flat plate shape includes: a conductive vacuum chamber having a recessed portion which is configured to cause a processing object portion of at least one side of the workpiece having a flat plate shape to be disposed in the recessed portion and a peripheral edge portion which is provided outside the recessed portion to be continuous with the recessed portion; a holding member configured to hold the workpiece to be separated and insulated from the peripheral edge portion; a voltage application unit configured to apply a voltage between the workpiece and the vacuum chamber; and an insulating layer configured to cover a portion of the peripheral edge portion facing the workpiece.