A silent discharge type plasma generator comprising a dielectrics, one set of electrodes disposed oppositely across the dielectrics, and an ac power supply for applying an ac voltage to between the electrodes to cause discharging, plasma being formed by supplying gas to a discharge-generating discharge space. At least one of the electrodes consists of a conductive feeding thin film formed on the dielectrics, and, when the dielectrics is damaged to generate arc discharge between the electrodes, that arc discharge-generated portion of the feeding thin film is eliminated or oxidized to stop arc discharger generation.