A mounting apparatus includes a chassis, a mounting tray, a supporting tray, and a securing member rotatably attached to the supporting tray. The mounting tray secures a first end of an expansion card. The supporting tray includes a pivoting portion. The pivoting portion includes a blocking portion, and the blocking portion includes a front side and a back side. The securing member includes a driving portion. The securing member is rotatable relative to the supporting tray between a locked position and an unlocked position. In the locked position, the driving portion abuts the front side of the blocking portion, and the securing member and the supporting tray together sandwich the second end of the expansion card therebetween. In the unlocked position, the driving portion abuts the back side of the blocking portion, and the securing member is disengaged from the second end of the expansion card.