A plasma control apparatus includes a power source unit, a resonance producing unit, and a voltmeter. The resonance producing unit includes an LC circuit formed by a coil L1 and a capacitor C1 connected to each other, and a sensor S2 configured to detect a phase difference between current flowing in and voltage applied to the LC circuit, and the capacitor C1 of the LC circuit has a capacitance larger than an expected capacitance of the plasma P. The power source unit 1 configured to control the magnitude of radio-frequency power to be supplied in such a manner as to bring the voltage measured with the voltmeter 5 close to a set voltage as a target, and controls the frequency of the radio-frequency power to be supplied in such a manner as to minimize the phase difference detected with the sensor S2.