A non-directional frequency generator spark prevention apparatus including a plurality of electric connections connected with a direct current power source, i.e., brushes, and a commutator for converting direct current waveform inputted through the brushes into alternating current waveform by rotational movement thereof, and for outputting the alternating current waveform. A voltage pulse controlling part is connected between the brushes of the non-directional frequency generator, while having a resistor and a transistor which are connected in series with each other, and the transistor is operated synchronously with the rotation of the commutator of the non-directional frequency generator. By controlling the electric current to flow through the transistor during the brush-off period, a spark production during the brush-off period can be prevented. Further, by controlling the transistor to be turned off during a predetermined period between a predetermined time of the brush-off period to a predetermined time of the brush-on period, the electric current does not flow through the transistor at the beginning of the brush-on period, and accordingly, the spark production at the beginning of the brush-on period is prevented. A corresponding pulse generating part includes a photo-interrupter and a photo sensor, for generating a predetermined pulse waveform corresponding to the rotation of the commutator. Based on the pulse waveform, the transistor is operated, and accordingly, the transistor precisely synchronizes with the rotation of the commutator of the non-directional frequency generator.