A power source device includes a capacitive load; and an AC power source, as a voltage source, which applies AC voltage to the capacitive load. A series circuit composed of an inductor and a capacitor is connected to the AC power source. A series circuit composed of a load inductor and the capacitive load is connected in parallel to one of the inductor or the capacitor. If an inductance of the inductor is defined as Lp, a capacitance of the capacitor is defined as Cp, an inductance of the load inductor is defined as Ls, an equivalent capacitance of the capacitive load is defined as Cs, and a frequency of the AC power source is defined as fv, the following expressions are satisfied, 0.8/((2π·fv){circumflex over ( )}2)