A support device includes a support element, a plurality of legs rotatably connected to the support element which can be rotated to be changed from an unfolded state and a folded state, and a main body sleeves the support element. When the legs are rotated to be in the unfolded state, the legs cooperate with the support element to support an electronic device, and when the legs are rotated to be in the folded state, the main body sleeves on the support element receiving the legs.