An apnea preventing stimulation apparatus in which a conductive unit 21 is attached to a mental region P of a patient and electric pulses conduct from the conductive unit 21 to the mental region P of the patient to thereby apply stimulation thereto. The apparatus includes a stimulus generating means 13 that outputs, across output terminals 22A, 22B of the conductive unit 21, stimulation signals which alternately repeat, for a preset time, a conduction period Ta during which electric pulse groups S, S comprising plural electric pulses are generated and a pause period Tb during which no electric pulse groups S, S are generated. Hence, without monitoring a respiratory condition during sleep, the upper airway obstruction can be quickly prevented. Further, as the stimulation signals can be applied to the patient irrespective of presence or absence of respiration of the patient, the patient hardly awakes by sensing the stimulation signals.
