An adjusting mechanism for adjusting rotary angle is disclosed in the present invention. The adjusting mechanism includes a bracket. The bracket includes a base, a first supporting portion disposed on a first lateral side of the base, and a second supporting portion disposed on a second lateral side of the base. A pivot hole is formed on the first supporting portion. The adjusting mechanism further includes a clamp disposed by a side of the base and located in a position corresponding to the first and the second supporting portion. The adjusting mechanism further includes at least one bridging component connecting to a lateral surface of the clamp, and a pivoting component. A pivot hole is formed on the bridging component. The pivoting component passes through the pivot holes on the first supporting portion and the bridging component, so as to pivot the first supporting portion relative to the bridging component.