Abstract: Disclosed is a method of ionizing surfaces of polymer-molded goods to intercept electromagnetic waves passing therethrough and to prevent the polymer-molded goods from being electrically charged. The method includes maintaining a main chamber and pre-chambers located before and after the main chamber under pressure of 105 torr using a vacuum pump, holding objective products by a spring holder on a carrier of an inlet chamber, transferring the objective products through a preheating chamber and the first pre-chamber into the main chamber, generating plasma by heating of a filament or arc generation of an ionization gun while controlling an ion beam current of electric power supplied to an ion generating gun, adding helium, argon, or nitrogen into the plasma to yield gas cations, irradiating the gas cations to the objective products, and discharging the resulting ionized products through the pre-chamber and an outlet chamber.