An apparatus for plasma treatment, capable of plasma-treating works of resin material by irradiating the surfaces of the works with a microwave discharge plasma within a vacuum reaction chamber, comprises a plurality of long plasma-irradiating tubular pipes, each of which is provided along the length thereof with numerous small holes for injecting plasma, and at least one plasma-irradiating straight pipe disposed with its free end opening toward a section to which the plasma is hard to flow. At least one second plasma-irradiating pipe is located movably to an optional position within the reaction chamber. A method for surface plasma-treatment comprises dividing a microwave generated in a magnetron in a plurality of microwaves by a distributor, introducing the divided microwaves into a plurality of plasma generating mechanisms, respectively, and introducing plasmas generated in the respective plasma generating mechanisms intothe reaction chamber through a plurality of plasma introducing ports, respectively, formed in the wall of the reaction chamber.