PURPOSE: To improve the durability of the motor-driven toothbrush of which the toothbrush part is fixed to a main body part by force feeding.

CONSTITUTION: A large diameter stick part 22 to be force-fed into an inlet side large diameter hole part 32 of a toothbrush part 2 is provided at one end of a main body part 1. A projecting part 24 is provided on a large diameter stick part tip face 25 and a small diameter projecting part 23 to be force-fed into a deep side small diameter hole part 33 of the toothbrush 2 is formed at the tip of this projecting part 24. The projecting part 24 is provided with a reinforce part 20 for linking the large diameter stick part top end face 25 and the small diameter projecting part 23 with a smooth recessed curved surface. The reinforce part 20 is formed in the shape not to be brought into contact with a tapered part 34 for linking the inlet side large diameter hole part 32 and the deep side small diameter hole part 33.