Provided are an electric toothbrush and its drive motor, which comprises a U-shaped magnetic yoke, a rotary output component, a second magnetic yoke and four permanent magnets. The two support legs of the U-shaped yoke are respectively wound with coils, enabling the two leg end faces to generate alternating magnetic poles under the control of circuit. The four magnets are centrosymmetrically disposed about a rotatory central line, the first and the fourth magnet are of the same polarity, the second and the third magnet are of the same polarity； the first and the second magnet are of the opposite polarity, disposed corresponding to the first leg； the third and the fourth magnet are of the opposite polarity, disposed corresponding to the second leg. Under the control of circuit, the driving permanent magnets drive the second yoke and the rotary output component to reciprocatively rotate about the rotatory central line.
