A folding device includes a main body, two connecting members respectively pivotally connected to the main body, and a locking assembly. Each connecting member includes an engaging portion. The locking assembly includes first and second hooking members, a lever, and an axial member. The first hooking member and the lever are pivotally connected to the main body. The axial member is inserted through the main body, the first hooking member and the lever. The second hooking member is pivotally connected to the lever. The first hooking member includes a first hooking portion, and the second hooking member includes a second hooking portion. The lever is pivotable with respect to the main body between locking and releasing positions.