An automated external defibrillator comprising: a detector adapted to detect an abnormality of the automated external defibrillator; and a notifier adapted to notify a user of the detection of the abnormality within a predetermined period when the detector has detected the abnormality; wherein: the notifier has a display unit that includes a light source, and a sounder adapted to generate an alert sound; the display unit is adapted to execute a first mode and a second mode alternately and one or more times respectively, so that the display unit makes the light source emit light with a first intensity in the first mode, and the display unit either makes the light source emit light with a second intensity lower in power consumption than the first intensity, or makes the light source not emit light in the second mode; the sounder is adapted to execute a third mode and a fourth mode alternately and one or more times respectively, so that the sounder generates the alert sound with a third intensity in the third mode, and the sounder either generates the alert sound with a fourth intensity lower in power consumption than the third intensity, or does not generate the alert sound in the fourth mode; characterized in that at least a half part of each of periods in which the first mode is executed overlaps timewise with a corresponding one of periods in which the fourth mode is executed; and at least a half part of each of periods in which the third mode is executed overlaps timewise with a corresponding one of periods in which the second mode is executed. a detector adapted to detect an abnormality of the automated external defibrillator; and a notifier adapted to notify a user of the detection of the abnormality within a predetermined period when the detector has detected the abnormality; wherein: the notifier has a display unit that includes a light source, and a sounder adapted to generate an alert sound; the display unit is adapted to execute a first mode and a second mode alternately and one or more times respectively, so that the display unit makes the light source emit light with a first intensity in the first mode, and the display unit either makes the light source emit light with a second intensity lower in power consumption than the first intensity, or makes the light source not emit light in the second mode; the sounder is adapted to execute a third mode and a fourth mode alternately and one or more times respectively, so that the sounder generates the alert sound with a third intensity in the third mode, and the sounder either generates the alert sound with a fourth intensity lower in power consumption than the third intensity, or does not generate the alert sound in the fourth mode; characterized in that at least a half part of each of periods in which the first mode is executed overlaps timewise with a corresponding one of periods in which the fourth mode is executed; and at least a half part of each of periods in which the third mode is executed overlaps timewise with a corresponding one of periods in which the second mode is executed. the notifier has a display unit that includes a light source, and a sounder adapted to generate an alert sound; the display unit is adapted to execute a first mode and a second mode alternately and one or more times respectively, so that the display unit makes the light source emit light with a first intensity in the first mode, and the display unit either makes the light source emit light with a second intensity lower in power consumption than the first intensity, or makes the light source not emit light in the second mode; the sounder is adapted to execute a third mode and a fourth mode alternately and one or more times respectively, so that the sounder generates the alert sound with a third intensity in the third mode, and the sounder either generates the alert sound with a fourth intensity lower in power consumption than the third intensity, or does not generate the alert sound in the fourth mode; characterized in that at least a half part of each of periods in which the first mode is executed overlaps timewise with a corresponding one of periods in which the fourth mode is executed; and at least a half part of each of periods in which the third mode is executed overlaps timewise with a corresponding one of periods in which the second mode is executed.