PURPOSE: To continuously carry out plasma treatment with good operability and treatment efficiency, by charging a material to be treated into a closable container having a valved piping for gas suction and discharge and plasma introduction and moving the container from a previous vacuum zone, plasma treating zone and purging zone one after another.

CONSTITUTION: A material to be treated 7 (a molded resin article in the form of simple part) is charged into a container 1 having an outlet and inlet for the material to be treated 7, door part for closing the outlet and inlet and at least one valved piping for gas suction and discharge and plasma introduction, and the container 1 is placed on a transfer apparatus 6 for moving a given distance, stopping and further moving after a given time and evacuated to reduced pressure in a previous vacuum zone by a vacuum pump 2 one after another. A gas in the plasma state from a plasma generating part 3 is introduced into the container 1 in a plasma treating zone while evacuating the container 1 by a vacuum pump 2-6 to treat the material 7 for a given time and a purging gas 5 is made to flow into the container 1 to purge the interior thereof and take out the treated material 7.