As a method of compensating for the voltage drop on the de side of ferroresonant dc stabilized power supplies, a magnetic-only controlled power supply was developed. When a de magnetic field is applied in the direction of diameter of a saturable ring core, using the saturation flux density, that is, resonant voltage change, by de load current feedback to an electromagnet positioned in the diametric direction, the resonant volt;ige is altered and output voltage stabilization is achieved. By increasing the operation frequency of the power supply, miniaturization is achieved and simultaneously, as a feedback control method, is expressed in a block diagram. An investigation was made on the power supply design method and the response to various disturbances. As a result, design criteria were established to make the steady-state output voltage error zero. The transient response simulation was verified to explain well the experimental result.