A mounting apparatus includes a drive bracket and a securing piece. The drive bracket includes a bottom plate and a side plate. A separating plate is located on the bottom plate to divide the drive bracket into a first portion and a second portion. The first portion defines an engaging hole. The second portion defines a first slide groove. An elastic piece is mounted on the side plate. The elastic piece defines a receiving hole. The securing piece is mounted on the one data storage device. The securing piece includes a clip engaged in the engaging hole to mount the first data storage device in the first portion. A first sliding block is mounted on another data storage device. The elastic piece is elastically bent to allow the first sliding block to slide in the first slide groove, and the first sliding block is engaged in the receiving hole.