Provided is a plasma control method including applying gas to a chamber having a wafer loaded therein, generating plasma by applying both radio frequency (RF) power associated with a first voltage at a first frequency and a second voltage at a second frequency that is lower than the first frequency to the chamber for a first time, cutting off the RF power after the first time elapses, continuously applying the second voltage of the second frequency to the chamber for a second time, cutting off the second voltage after the second time elapses, continuously maintaining an off state of the RF power and an off state of the voltage for a third time, and performing an etching process on the wafer by using the plasma formed by the RF power and the second voltage after the third time elapses, wherein the RF power is a sine wave, and the second voltage is a square wave of a periodic pulse form.