A power source circuit comprising: a pair of supply lines (3, 4); a power conversion circuit configured to convert by a switching operation at least one of a frequency and a voltage of an alternating voltage from an alternating power source connectable to the power conversion circuit via said pair of supply lines (3, 4); an excess current protection element provided for one supply line of the pair of supply lines; a first line bypass capacitor (C 1) connected between a ground line and the one supply line; a second line bypass capacitor (C 2) connected between the ground line and the other one of the pair of supply lines; and either an inductor is provided for the other supply line, wherein, when a capacitance value of the first line bypass capacitor (C 1) is defined as C1, a capacitance value of the second line bypass capacitor (C 2) is defined as C2, an inductance value of the one supply line including an inductance component of the excess current protection element is defined as L1, an inductance value of the another supply line including an inductance component of the inductor is defined as L2, and an angular frequency of switching noise is defined as ω[rad/s], the inductance value of the inductor is set to satisfy a following expression: 2 ⁢ C 1 - C 2 - 2 ⁢ ω 2 ⁢ L 1 ⁢ C 1 ⁢ C 1 + C 2 3 ⁢ C 2 ⁢ 1 - ω 2 ⁢ L 1 ⁢ C 1 + C 2 ⁢ L 1 < L 2 < 2 ⁢ C 1 - C 2 - 2 ⁢ ω 2 ⁢ L 1 ⁢ C 1 ⁢ C 1 + C 2 C 2 ⁢ 1 - ω 2 ⁢ L 1 ⁢ C 1 + C 2 ⁢ L 1 or a first choke coil is provided for the one supply line and a second choke coil is provided for the other supply line of the pair of supply lines, wherein, when an inductance value of the one supply line including an inductance component of the first choke coil) and the excess current protection element is defined as L1, an inductance value of the other supply line including an inductance component of the second choke coil is defined as L2, a capacitance value of the first line bypass capacitor (C 1) is defined as C1, a capacitance value of the second line bypass capacitor (C 2) is defined as C2, the capacitance values of the first line bypass capacitor and the second line bypass capacitor are set to satisfy a following expression: 2 ⁢ L 2 L 1 - 1 ≤ C 1 C 2 < 1 a pair of supply lines (3, 4); a power conversion circuit configured to convert by a switching operation at least one of a frequency and a voltage of an alternating voltage from an alternating power source connectable to the power conversion circuit via said pair of supply lines (3, 4); an excess current protection element provided for one supply line of the pair of supply lines; a first line bypass capacitor (C 1) connected between a ground line and the one supply line; a second line bypass capacitor (C 2) connected between the ground line and the other one of the pair of supply lines; and either an inductor is provided for the other supply line, wherein, when a capacitance value of the first line bypass capacitor (C 1) is defined as C1, a capacitance value of the second line bypass capacitor (C 2) is defined as C2, an inductance value of the one supply line including an inductance component of the excess current protection element is defined as L1, an inductance value of the another supply line including an inductance component of the inductor is defined as L2, and an angular frequency of switching noise is defined as ω[rad/s], the inductance value of the inductor is set to satisfy a following expression: 2 ⁢ C 1 - C 2 - 2 ⁢ ω 2 ⁢ L 1 ⁢ C 1 ⁢ C 1 + C 2 3 ⁢ C 2 ⁢ 1 - ω 2 ⁢ L 1 ⁢ C 1 + C 2 ⁢ L 1 < L 2 < 2 ⁢ C 1 - C 2 - 2 ⁢ ω 2 ⁢ L 1 ⁢ C 1 ⁢ C 1 + C 2 C 2 ⁢ 1 - ω 2 ⁢ L 1 ⁢ C 1 + C 2 ⁢ L 1 or a first choke coil is provided for the one supply line and a second choke coil is provided for the other supply line of the pair of supply lines, wherein, when an inductance value of the one supply line including an inductance component of the first choke coil) and the excess current protection element is defined as L1, an inductance value of the other supply line including an inductance component of the second choke coil is defined as L2, a capacitance value of the first line bypass capacitor (C 1) is defined as C1, a capacitance value of the second line bypass capacitor (C 2) is defined as C2, the capacitance values of the first line bypass capacitor and the second line bypass capacitor are set to satisfy a following expression: 2 ⁢ L 2 L 1 - 1 ≤ C 1 C 2 < 1