A support device is configured to receive an electronic device. The support device includes a base, a holder rotatably mounted to the base, a semi-gear engaged with the holder, an eccentric gear including an shaft inserted into the holder, a wheel module selectively to drive one of the semi-gear and the eccentric gear to rotate, and a rotating module fixed to the wheel module; when the rotating module is rotated in a first direction, the wheel module drives the semi-gear to rotate, so as to make the holder to move up and down with respect to the base; when the rotating module is rotated in a second direction reversed to the first direction, the wheel module drive the eccentric gear to rotate, so as to drive the holder to rotate with respect to the base to adjust an angle between the holder and the base.