An exemplary mounting apparatus for an expansion card with an end plate includes a mounting bracket, and a retaining member slidably attached to the bracket. The mounting bracket includes a supporting panel having a protruding bridge extending therefrom, and a pair of flanges defining a pair of slanting railways therein. The retaining member includes a hook depending from a retaining wall, and a pair of sliding bars extending from a pair of sidewalls. The sliding bars slide along the railways to sandwich the end plate of the expansion card between the supporting panel and the retaining wall. The hook engages with the protruding bridge to lock the retaining member to the mounting bracket.