A mounting apparatus includes a chassis, a mounting piece and a securing member. The chassis includes a rear plate and a side plate. The rear plate includes a supporting panel, and a positioning slot is defined in the rear plate. The side plate includes a flange. The mounting piece includes an engaging portion. The securing member includes a first securing panel rotatably attached to the supporting panel and a second securing panel. A retaining piece extends from the second securing panel in a first direction, and a positioning piece extends from the second securing panel in a second direction substantially perpendicular to the first direction. The retaining piece is engaged in the positioning slot, the positioning piece is located between the flange and the rear plate, and the flange is secured to the rear plate.