A brush actuator of the automatic toothbrush is provided, in which structure is simple and the manufacture is facilitated and which shortens the assembly time of the part. A brush actuator of the automatic toothbrush is constituted as follows. The toothbrush(10) is formed to separate the body portion and head unit. The operated left-right operation type toothbrush body(13') is installed at the head unit. The rotating brush(14) rotated by the operation of the left-right operation type toothbrush body is installed. The driving part(15) operating the toothbrush body is installed inside the body portion. In the end part of the body portion, the dry cell connecting part(16) screwing the dry cell and the cap(17) fixing the dry cell connecting part are connected.
