Abstract: A transformer separable/detachable between a primary winding and a secondary winding, has a capacitor connected parallel to the secondary winding. A high-frequency AC voltage supplied to the primary winding of the transformer generates an induced voltage in the secondary winding. The secondary winding transmits electrical power to a load in non-contact manner. Either the output voltage remains constant as the output current varies, or vice versa. Taking as a first condition a fact that at the time of a maximum load, the time of the reversal of the voltage polarity of the primary winding substantially coincides with the time when an oscillating voltage of the capacitor reaches a maximum or minimum value. Taking as a second condition a fact that at the time of a minimum load, the time of the reversal of the voltage polarity of the above-mentioned primary winding substantially coincides with the time when the oscillating voltage of the above-mentioned capacitor completes one cycle.