A mounting apparatus for securing a motherboard (30) defining several locking holes (32) includes a chassis (10), a lever (20) and a tray (40). The chassis includes a bottom panel (11) and a mounting member (14). Several standoffs (17, 18) are arranged at the bottom panel. A locating portion (144) is formed on the mounting member. The lever pivotally mounted on the bottom panel includes a securing end (242). A fixing post (224) protrudes from the lever. The tray supporting the motherboard defines an opening (442) for receiving the fixing post therein. The lever is rotated from an unlocked position to a locked position. The fixing post pushes the tray. The motherboard slides on the bottom panel until the securing end is disposed on the locating portion. The motherboard is thus mounted in the chassis.