The support apparatus includes a base, a pair of supporting arms, and a locking element. The base defines at least one engaging projection on a top thereof. Each supporting arm includes a body having a first curved end and a second curved end extending from the two opposite ends thereof. The first curved end is connected to the base and the second curved end is positioned in the locking element. The locking element defines a rail, and two curved protruding blocks extend from the two opposite ends of the rail. When the at least one engaging projection is engaged with a side of an external device, the supporting arms rotate relative to the base and the locking element sits on top of the external device, and the rail and the protruding blocks holds another side of the external device.