A substrate-treating apparatus includes a process chamber including a space therein, a lower electrode which is in the space of the process chamber and supports the substrate, an upper electrode which faces the lower electrode in the process chamber, a high frequency supply line which includes a feed point which applies a high frequency power to the lower electrode, and a modulator which asymmetrically supplies a dielectric substance to a lower portion of the lower electrode with reference to a center portion of the lower electrode.