A rotating device includes a rotating shaft, a rotating disc, a left clamping disc, a right clamping disc, an upper clamping disc, and a recovering component. The upper clamping disc, the left clamping disc, and the right clamping disc are sleeved on the rotating shaft. The upper clamping disc fixes the rotating disc, the left clamping disc, and the right clamping disc on the rotating shaft. The recovering component abuts between a side of the left clamping disc and a side of the right clamping disc. A clamping zone is formed between the other side of the left clamping disc and the other side of the right clamping disc for clamping the detecting disc, and an overlapping zone is formed between the side of the left clamping disc and the side of the right clamping disc and opposite to the clamping zone.