The present invention relates to a plasma treating method and apparatus therefor. The plasma treating method comprises the steps of forming a treating gas into a plasma under reduced pressure, utilizing the plasma to treat a specimen cooled to a low temperature less than 0.degree. C. under reduced pressure, and maintaining at least an exposed surface to an atmosphere at which the specimen is treated except a specimen place surface of a specimen table on which the specimen is placed at a temperature above a dew point temperature of gases under the atmosphere; and a plasma treating apparatus comprises a treating chamber, means for reducing and exhausting the interior of the treating chamber, means for introducing a treating gas into the treating chamber, means for forming the treating gas into a plasma, a specimen table on which the specimen treated by utilizing the plasma is placed within the treating chamber, means for cooling the specimen table so as to be able to cool the specimen to a low temperature less than 0.degree. C., and means for maintaining at least an exposed surface within the treating chamber except a specimen place surface of the specimen table at a temperature above a dew point temperature of gases within said treating chamber, whereby even if the specimen table is cooled to a low temperature less than 0.degree. C., adsorption of the atmospheric gas to the exposed surface within the treating chamber which is at least a pressure-reduced atmosphere exposed surface except a specimen place surface of the specimen table is suppressed, and principally the occurrence of foreign matter can be prevented and the lowering of the yield of the specimen causes by the foreign matter can be prevented.