An electric toothbrush includes a handle, a brush head with bristles fixed thereto, a reciprocating bar, an actuator that moves the reciprocating bar back and forth, an actuator receiving recess, an engaging device that engages the brush head with the reciprocating bar so that the brush head moves relative to the reciprocating bar in either penetration mode or polishing mode and a selection device that places the engaging device either in the penetration mode or the polishing mode. The reciprocating bar is protruded from the handle and received in the actuator receiving recess. The brush head moves together with the reciprocating bar in the polishing mode. The brush head is free to move relative to the reciprocating bar within a predetermined distance in the penetration mode. The longitudinal axis of the brush head is inclined from the longitudinal axis of the handle with a predetermined angle.