A drive motor for electric toothbrush, comprising: a U-shaped magnetic yoke, a control circuit, and a rotary output component, the rotary output component can reciprocatively rotate about a rotatory central line; a second magnetic yoke, the second magnetic yoke is disposed at one end of the rotary output component near the U-shaped magnetic yoke; and four permanent magnets (410, 420, 430, 440), the permanent magnets are fixedly mounted on the second yoke; the four permanent magnets (410, 420, 430, 440) are centrosymmetrically disposed about a rotatory central line, they are a first permanent magnet, a second permanent magnet, a third permanent magnet and a fourth permanent magnet; characterized in that: the U-shaped magnetic yoke has a first support leg and a second support leg, and the first support leg and the second support leg are respectively wound with coils; the control circuit is electrically connected to the coils and generates alternating pulses, to generate alternating magnetic poles at the end faces (111, 121) of the two support legs of the U-shaped magnetic yoke; the outer faces of the first permanent magnet and the fourth permanent magnet are of the same polarity, and the outer faces of the second permanent magnet and the third permanent magnet are of the same polarity; the outer faces of the first permanent magnet and the second permanent magnet are of the opposite polarity and are disposed corresponding to the end face of the first support leg; the outer faces of the third permanent magnet and the fourth permanent magnet are of the opposite polarity and are disposed corresponding to the end face of the second support leg; there is an air gap between the end faces (111, 121) of the permanent magnets (410, 420, 430, 440) and their corresponding support legs (110, 120), and under the control of the control circuit, the permanent magnets (410, 420, 430, 440) drive the second yoke and the rotary output component to reciprocally rotate about the rotatory central line. a U-shaped magnetic yoke, a control circuit, and a rotary output component, the rotary output component can reciprocatively rotate about a rotatory central line; a second magnetic yoke, the second magnetic yoke is disposed at one end of the rotary output component near the U-shaped magnetic yoke; and four permanent magnets (410, 420, 430, 440), the permanent magnets are fixedly mounted on the second yoke; the four permanent magnets (410, 420, 430, 440) are centrosymmetrically disposed about a rotatory central line, they are a first permanent magnet, a second permanent magnet, a third permanent magnet and a fourth permanent magnet; the U-shaped magnetic yoke has a first support leg and a second support leg, and the first support leg and the second support leg are respectively wound with coils; the control circuit is electrically connected to the coils and generates alternating pulses, to generate alternating magnetic poles at the end faces (111, 121) of the two support legs of the U-shaped magnetic yoke; the outer faces of the first permanent magnet and the fourth permanent magnet are of the same polarity, and the outer faces of the second permanent magnet and the third permanent magnet are of the same polarity; the outer faces of the first permanent magnet and the second permanent magnet are of the opposite polarity and are disposed corresponding to the end face of the first support leg; the outer faces of the third permanent magnet and the fourth permanent magnet are of the opposite polarity and are disposed corresponding to the end face of the second support leg; there is an air gap between the end faces (111, 121) of the permanent magnets (410, 420, 430, 440) and their corresponding support legs (110, 120), and under the control of the control circuit, the permanent magnets (410, 420, 430, 440) drive the second yoke and the rotary output component to reciprocally rotate about the rotatory central line.