Abstract: The connections device of an actuator for side mirrors of an automobile, for a back observation, is constructed by forming its main body made of synthetic resin material to reduce weight of an actuator itself and curtail a manufacture cost, and by inserting metal support plates into both sides of the main body inside so as to support and rotate the gear in a part having a danger of a damage caused owing to rotating components such as a gear etc. to prevent the main body from being damaged, whereby resulting in a light weight of the actuator and lessening a manufacture cost through a use of the main body made of the synthetic resin material, and in lengthening a life of components together with a maintenance of a mechanical strength through a use of the support plates made of metal inserted into both sides of the main body inside.