An ejection mechanism includes a top cover, a bottom cover having a first sidewall and a second sidewall, and a sliding assembly. The sliding assembly includes a sliding block and an elastic rod. The sliding block defines a containing groove which is divided into an insertion rail and an ejection rail. The sliding block is configured to move back and force between the first and second sidewalls. A first distal end of the elastic rod is fixed in a fixing hole of the first sidewall. When the card is inserted into the ejection mechanism, the second distal end slides along the insertion rail until the second distal end is locked in a joint of the insertion and ejection rails. When the second distal end of the elastic rod disengages from the locked position by an external force, the second distal end slides in the ejection rail.