An electric toothbrush of the present invention includes: a case having first and second drive shafts exposed therefrom, the first and second drive shafts being rotated in opposite directions and moved forward and backward respectively by a drive unit which is driven by a motor； first and second toothbrush bodies coupled to the first and second drive shafts by first and second coupling units respectively, so as to transmit the rotational force and forward and backward motions of the first and second drive shafts； a brush installed at the ends of the first and second toothbrush bodies so as to clean teeth by the rotational force and forward and backward motions transmitted to the first and second toothbrush bodies； and a third toothbrush body having an auxiliary brush, which is coupled to a third drive shaft of the drive unit installed in the case and rotated at a predetermined angle so as to brush occlusal surfaces of teeth.
