The present invention relates to an electric circuit having a transformer capable of functioning as a buffer inductor, and a magnetic stimulator using the transformer. The electric circuit of the present invention includes a power supply unit, and rectification means for rectifying current from the power supply unit. A transformer has an inductor on a primary side connected to the power supply unit. A capacitor is connected to an inductor on a secondary side of the transformer. Reverse flow prevention means is connected in series between the capacitor and the transformer to prevent charges stored in the capacitor from reversely flowing toward the transformer. A discharge inductor receives charges stored in the capacitor as discharge current and forms a magnetic field. First switching means turns on or off flow of the discharge current that flows in one direction. Bypass means causes current to flow in one direction.