In order to provide a plasma processing apparatus or method with improved processing uniformity, a plasma processing apparatus includes: a processing chamber which is disposed inside a vacuum container; a sample stage which is disposed inside the processing chamber and has a top surface for placing a wafer corresponding to a processing target thereon; an electric field forming part which forms an electric field supplied into the processing chamber; a coil which forms a magnetic field for forming plasma inside the processing chamber by an interaction with the electric field; and a controller which increases or decreases intensity of the plasma inside the processing chamber by repeatedly increasing or decreasing intensity of the magnetic field formed by the coil at a predetermined interval, wherein the wafer is processed while the plasma is repeatedly formed and diffused.